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Fosi Audio ZA3 - Initial Review

I presume people have seen the Fosi Audio ZD3 this looks like the perfect preamp for the ZA3 (and the V3-Mini):


From what I gather their will be a kickstarter campaign
Well the price is right for sure but if you do not have multiple sources you need to hook up than the ZA3 is like an intergrated amp since it has it's own volume control that controls it's volume and anything hooked up to the aux output/sub out etc.....Not sure if they make just source switching boxes like they did back when dinosaurs roamed the Earth but those where not preamps. I know I am dating myself now.
 
Well the price is right for sure but if you do not have multiple sources you need to hook up than the ZA3 is like an intergrated amp since it has it's own volume control that controls it's volume and anything hooked up to the aux output/sub out etc.....Not sure if they make just source switching boxes like they did back when dinosaurs roamed the Earth but those were not preamps. I know I am dating myself now.
The term “Integrated Amp” refers to an amplifier, combined with a preamp, with switching between at least two sources. To that effect, the ZA3 is not an integrated amp, as it neither has a preamp circuit, nor does it offer switching between sources. It is an amplifier with an attenuator, nothing more.

Preamps come in a few flavors: passive preamps, which are unpowered, deliver zero gain and essentially switch between sources, with an attenuator knob to limit input gain from sources to the amplifier. There are a few available, typically at entry level price points; the Schiit Sys is a prime example. An active preamp is powered and can offer a modicum of gain and often has tone controls, in addition to switching between sources. If you take an amplifier and a preamp and put them in the same box, you now have an integrated amp.

With regard to offerings from Fosi Audio, the V3 and ZA3 are amps with attenuation; the V3 mono is a straight power amp without volume control. The P3 is a preamp with volume and tone controls, with just a single source. The P4 is a preamp with multiple sources. The MC331 is an integrated amp without volume control an onboard DAC. The ZD3 is marketed as a desktop DAC, however, it also offers switching between digital sources and a volume control, so it could theoretically be used as a preamp, as long as you don’t have analog sources.
 
Yes but it has volume control that not only controls the amps out put but can control another devices output like a subwoofer. Most little amps with a volume knob only control the Amp itself nothing else. The Ayima 07 Max I think it is will not control a subwoofer even though it has an output.

My Yamaha RS-202 Stereo Receiver will not control any outboard devices volume even though it is a 100wpc Reciever. I know because I hooked it up to my Carver amp when I first got back into audio before I found my Carver pre-amp in the attic and hooked that up. I had to control the amp output with the front mounted individual gain controls on the amp.


So what do we call an amp that has some of the functionality of a "Preamp" we do not have a name for an amp that has some preamp functionality but not all preamp functionality! Volume control is not traditionaly something that an amplifier does that is the domain of the preamplifier. Source matching or in this cause controling the volume on the output side for some aux device is also not a function of an amplifier. Thus having no intermediate term I correctly called it "intergrated" because you do not need a preamp in order to use it. Now if the industry comes up with a new name for amps that have some preamp functions but no switching I will gladly use that new name!

AI answer "
  • Amplification:
    The primary function of a preamp is to boost the signal from a source (like a microphone, turntable, or guitar) to a stronger level.

  • Line Level:
    Preamps raise the signal to "line level," which is the standard operating level for most audio equipment.

  • Source Matching:
    Preamps are designed to handle signals from various sources, such as phono cartridges (turntables), microphones, and instruments, ensuring compatibility with subsequent audio equipment.

  • Sound Shaping:
    In addition to amplification, preamps can also impart a unique sonic character or "color" to the audio signal, depending on their design and components.

  • Vintage Preamps:
    Vintage preamps, often featuring tube technology, are known for their warm, rich, and sometimes slightly compressed or "colored" sound, which can be desirable for certain applications. "



 
Since we have been pontificating on whether removing all unused op-amps from a ZA3 improves sound quality, I asked Grok AI the question "Does removing unused op-amps from a Fosi ZA3 amplifier improve sound quality?" The answer is much more complete, nuanced and well thought out than I expected.

Removing unused operational amplifiers (op-amps) in a Fosi ZA3 amplifier when running it in mono mode may improve sound quality, based on user experiences shared within the audiophile community, though the effect is subjective and not universally guaranteed. In mono mode, the Fosi ZA3 uses only the right channel output, meaning the left channel op-amp and potentially others (like those tied to unused features such as the subwoofer output) are not actively contributing to the signal path. Some users have reported that removing these unused op-amps can result in a cleaner, more open sound, possibly by reducing electrical noise or interference in the circuit.

For instance, one user on the Fosi Audio Global Community forum noted that after removing the unused op-amps from their ZA3s in mono mode—leaving only a Sparkos SS3602 in the right channel output—the sound became "a lot more open and clear," likening the previous sound to having "speaker grills on." This suggests that unused op-amps might introduce subtle noise or load effects, even if they’re not actively amplifying a signal. Another user confirmed they removed the left channel op-amp when using RCA inputs in mono mode without issues, implying the circuit can function safely with only the right channel op-amp in place.

However, there’s no official technical documentation from Fosi Audio explicitly stating that unused op-amps degrade sound quality or that their removal is necessary for optimal performance in mono mode. The ZA3’s design includes five swappable op-amps: one for each stereo channel (left and right), one for XLR input, and two for the subwoofer output. In mono mode, only the right channel op-amp is critical, and the others may remain idle depending on your setup (e.g., no subwoofer or XLR input). Theoretically, idle op-amps could still draw power or introduce minor crosstalk or capacitance effects, but this would likely be minimal given the ZA3’s Class-D architecture and reported SINAD of 89 dB, which indicates a low noise floor (150 μV).

The improvement, if any, might depend on factors like the quality of the stock NE5532 op-amps, the replacement op-amps (e.g., Sparkos SS3602 or MUSES02), and the listener’s sensitivity to subtle changes. Some audiophiles argue that simplifying the signal path by removing unnecessary components aligns with a "less is more" philosophy, potentially reducing distortion or interference. Yet, others who’ve tested both configurations (e.g., replacing both left and right op-amps versus just the right one) report mixed results, with some preferring the fuller upgrade for consistency, even in mono.

Practically, removing unused op-amps is safe as long as you’re not using the associated features (e.g., subwoofer out or stereo mode), and it’s a reversible tweak. If you’re running two ZA3s in mono with, say, Sparkos SS3602 op-amps in the right channels, you could experiment by removing the left channel op-amps and listening for differences in clarity, imaging, or background noise. Given the subjective nature of audio perception and the lack of definitive measurements proving a significant change, it’s worth trying if you’re curious—your ears will be the judge. Just ensure proper handling to avoid damaging the circuit, and consider reapplying thermal paste if you open the unit, as suggested by some community members to prevent overheating.
 
Groc is going to end up writing speeches and making political campaign recomendations soon!
I have been using Grok for a lot of technical inquiries and am quite impressed with it. The question I asked about the ZA3 is one that is way off the beaten path. To get such an accurate and useful answer was totally unexpected. This has been the same with about everything on which I have asked for a response. I have needed a new pair of earbuds to wear for exercising so I put in the parameters of what I wanted like price, noise cancelling, etc. It gave me 3-4 suggestions so I picked one and ordered it off of Amazon. They are very close to being exactly what I wanted and what Grok described. This saved me a lot of time looking at websites, watching review videos and reading articles. From what I have seen, Grok is more capable than other AIs I have used and seems to be more refined and wording responses that seem to be closer to human generated. Where this tech goes in the next few years is exciting and scary as hell at the same time.
 
Generative AI at its best is simply plagiarism software. More typically, it’s like asking your dad an obscure & technical question when you’re 10: it just makes **** up. Since it basically scrapes the internet for information, it has little in the way of differentiating technically correct information from published research, and some guy on a forum who’s speculating for the hell of it. It’s a crutch that makes people dumber, as it spoon feeds them questionably credible data, rather than individuals doing proper research, getting their info from established and verified sources. As far as sources go, I would rate it below Wikipedia, “______ For Dummies” pamphlets, Joe Rogan, random YouTube videos and Cliff’s Notes.
 
Generative AI at its best is simply plagiarism software. More typically, it’s like asking your dad an obscure & technical question when you’re 10: it just makes **** up. Since it basically scrapes the internet for information, it has little in the way of differentiating technically correct information from published research, and some guy on a forum who’s speculating for the hell of it. It’s a crutch that makes people dumber, as it spoon feeds them questionably credible data, rather than individuals doing proper research, getting their info from established and verified sources. As far as sources go, I would rate it below Wikipedia, “______ For Dummies” pamphlets, Joe Rogan, random YouTube videos and Cliff’s Notes.
AI is just the latest in a long line of technology that has greatly advanced the human race. The same being said about AI was said about computers but here we are using them to our benefit. After computers it was smartphones but again here we are with nearly every human on the planet having one and being better off for it. Now it is AI and..... I remember at the introduction of the electronic calculator where it was supposed to be the beginning of the end of people using their brains. I think AI is going to have a similar impact as computers in that it will allow lightening fast computations, data analysis, extrapolation to outcomes, etc.

IMO, AI is going to be just another tool to be used like computers, calculators, smartphones, welders, robotics, etc. to advance our knowledge and technology. If you haven't, I suggest you use a capable AI like Grok, or others, to know personally what it can do. AI isn't all that far off from using search engines. It is just way more efficient at getting the information to the user. Like every new technology from nuclear fission to computers to smartphones etc. it can be used for good or bad. Smartphones have been overwhelmingly good for the human race by connecting people across the globe, educating people by giving them a vast amount of knowledge in the palm of their hand, allowing every smartphone user to be a reporter among many other positive outcomes from using one. Whether we like it, or not, AI is the next big technological advancement and will hopefully become a useful tool for humanity just like the past big advancements.
 
As a writer, visual artist and photographer, as well as musician, I find generative AI deeply offensive. It doesn’t create, it only copies and steals. Other AI has legitimate uses for parsing massive troves of data to identify trends and anomalies in say, astronomical or genetic research, for instance, but generative AI is merely a tool of the rich and powerful to steal from the creative classes.
 
As a writer, visual artist and photographer, as well as musician, I find generative AI deeply offensive. It doesn’t create, it only copies and steals. Other AI has legitimate uses for parsing massive troves of data to identify trends and anomalies in say, astronomical or genetic research, for instance, but generative AI is merely a tool of the rich and powerful to steal from the creative classes.
I understand exactly where you are coming from regarding impacts of major jumps in technology. I am a civil engineer and have worked in the design/consulting segment for all of my career. Up until personal computers came about in the early 1990s it took 3-4 people to complete a site plan design. Much of how a plan was prepared was by old school methods like hand drafting and manual calculations. There was some work completed using CAD software but it was very limited.

Then IBM released the PC, and shortly after, the PC could run on Windows software. At this point Autodesk and other software companies started offering incredibly advanced CAD software. The combination of PCs and CAD software reduced those 3-4 people down to a single engineer and much of the administrative support was no longer needed either. So around 75% of the engineering staff was laid off in a matter of just 2-3 years. It was a bloodbath. Fortunately, since I was a degreed engineer, I was spared. The people who were laid off found other employment. Some took government positions or just changed careers. One thing that did happen was people who embraced the new CAD technology were the ones who continued working in consulting firms. Fast forward to today and one civil engineer can do the work of two, or more, that was working in the late 1990s due to CAD software advancements over the years. Technological advancements have been eliminating jobs for millennia but the pace of advancement over the past 100 years is causing an acceleration of job loss.

There will be continual elimination and creation cycles in the job market. Many thought that the birth of the PC was going to put people out of work forever. What actually happened was PCs created tens upon tens of millions of new jobs in any number of market segments. I think AI will end up doing the same but it will take time for things to equalize. I know it isn't good for people to go through this transition period but there will be jobs that are created by AI technology. The humans needed to support AI is going to be massive just to maintain its support infrastructure. Then there will be spinoff industries created by AI. I think there will be a huge shift to trade jobs in the coming years or ones that require a human physical component.
 
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As a writer, visual artist and photographer, as well as musician, I find generative AI deeply offensive. It doesn’t create, it only copies and steals. Other AI has legitimate uses for parsing massive troves of data to identify trends and anomalies in say, astronomical or genetic research, for instance, but generative AI is merely a tool of the rich and powerful to steal from the creative classes.
I personally use it for performing complex math/calculations that I don't have the math depth for, such as converting THD+N ratings on amps to SINAD, or for generating visual representations of concepts that I want to see such as asking it to provide a graph combining a 2nd order low-pass filter versus a 4th order high-pass filter at 60Hz with reference level of 80dB.

-Ed
 
Merely using computers and using AI are not even remotely similar. I learned to draft using T-squares, triangles, Rapidiograph pens and transfer type. Using computers made my workflow much easier, making changes to layout, layering, color and typesetting child's play but it was still incumbent on me to make every creative decision.

Similarly, my recording studio is run on my laptop. A $3000.00 investment nets me better results than the $30,000.00 ADAT studio I had nearly 30 years ago. The quality of the music remains dependent on the human songwriting, musicianship and engineering.

As a photographer, my DSLR simplified my processes, a single card could hold a day's worth of shots, hundreds of rolls of film. Processing the photos was simplified, I could do it back in my trailer after the day was done and release the images the next day or sooner. My input was required at every step along the way: I still had to be at the right place at the right time to get the shot. While autofocus was a godsend, I still had to set the f-stop, make sure the light readings were correct, frame the image and pan the shot to capture everything. Back in my trailer, I still had to comb through hundreds of images to select the perfect photos from the dailys. I also had to do color and light corrections if needed or crop the images for better visual impact. While there was much that could be automated through batch processing, the results were inferior to doing each image individually, to completely put my artistic imprint on the shot.

Learning to type on typewriters back in the 80's was a chore. While there was a tactile quality to pressing the keys on the 1960's vintage Remington typewriter that I used in high school and my freshman year in college, it was a messy, painstakingly slow affair, especially considering that I suffered from mild dyslexia. the mess of the ribbons, whiteout and even having to redo entire pages made writing papers an excruciating task. I hated it. Word processing on a desktop eased a lot of the pain and certainly eliminated having ribbon ink on my fingertips and smudges of Whiteout on the pages, while autocorrect reduced my typos and cut and paste made editing my compositions much more straightforward and easy. At the same time, it was my responsibility to research the information, interpret the data that I'd found and compose it in a meaningful way, imprinting my stylistic flourishes to make my prose more engaging (or not). Over the course of time, writing went from a laborious task that I loathed and struggled with at every step, to a process that I relished and enjoyed, in no small part because of computers enabling me to overcome cognitive disabilities and better organize my thoughts.

The common thread above, is that while computers are a wonderful tool that eases workflow and facilitates creativity, they don't replace it. In each case, the success or failure of the end result is dependent on the individual who created it. It requires thoughtfulness, creativity and expertise in the intellectual and technical aspects to yield a acceptable result. Above, computers are a tool that allow individuals to channel their creativity and create works that reflect that individual's experiences. It still requires intellectual, social and emotional intelligence to achieve a successful outcome.

Generative AI, on the other hand, does none of that. It combs, parses, filters and contextualizes information, but it does not create. It steals. It requires no user intelligence, intellectual, social or emotional; it needs no artistic creativity or imagination and requires no experience. Generative AI is the death of expertise. Further, when I write and record a song, create an image, write an article, design a structure or capture a photo, I, the artist, own the output of my creativity until I sell it. Who owns AI? Corporations and their wealthy backers own it and its products, which are the result of theft. You don't own the results of your queries to Grok AI, its parent corporation does. AI bypasses the creativity of individuals (which it is wholly dependent upon) for corporate profit. Far from democratizing information, it robs it from creators and funnels the value directly to the billionaire class that developed it. Ai is always exploitive, using it at all promotes the exploitation of creative's work and personal data, since that how the models are built.

In summary, Al images, text, videos and music are created by fusing the creative work of real, human artists without their explicit permission; They are generated with the express purpose to avoid paying someone to create something unique. Countless artists, authors, musicians, animators and video producers with unique, original styles have had their entire portfolios fed into Al algorithms to copy their look, sound or methodologies. Many media publishers are already in the process of massively cutting or entirely eliminating their human artist workforces; Apropos to our interests, Spotify, for instance, uses AI generated "music" that copies established artists and places it in their playlists as filler of avoid paying their already meager royalties. Then there's the fact that Al uses tremendous amounts of energy and resources per use. For each Al prompt, it requires approximately .5L of water to cool the processors. Al's global water consumption is estimated to reach between 4.2 and 6.6 billion cubic meters by 2027; this is roughly equivalent to 4-6 times the annual water usage of Denmark.

Your usage of AI suggests an apathy towards the moral, environmental, and social issues I've outlined above.

If you'd like further reading, Here's a more in-depth and technically-oriented essay on how Generative Al functions and its social impacts: https://www.corralldesign.com/writing/ai-harm-hypocrisy
Energy usage: https://www.vox.com/climate/2024/3/28/24111721/climate-ai-tech-energy=demand-rising
Ethics of Generative Al: https://beautifulbizarre.net/2023/03/11/ai-art-ethical-concerns-of-artists/
 
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I personally use it for performing complex math/calculations that I don't have the math depth for, such as converting THD+N ratings on amps to SINAD, or for generating visual representations of concepts that I want to see such as asking it to provide a graph combining a 2nd order low-pass filter versus a 4th order high-pass filter at 60Hz with reference level of 80dB.

-Ed
It's amazing how generative AI knows everything about subjects I know nothing about, yet it's wrong 40% of the time regarding subjects where I have expertise.
 
It's amazing how generative AI knows everything about subjects I know nothing about, yet it's wrong 40% of the time regarding subjects where I have expertise.
You're suggesting that 40% of the math it is doing for me is wrong?

-Ed
 
I’m suggesting that I don’t trust the results from generative AI. YMMV.
And my point was there are good uses and there are bad uses, just like any other tool in life. A flat head screwdriver is best implemented for putting in and removing straight headed fasteners, not for prying open cans, in much the same way AI can be used for something but shouldn’t, yet should be used for others.

I guarantee you I will thoroughly screw the pooch trying to do those same math equations myself, if I even manage to pick the right ones in the first place.

If you can do it better, then do it. If you can’t, then don’t.

As for art, well, that is a different story. I personally prefer real art made by real people, since art is meant to be an expression of feelings and perspectives. What feelings or perspectives would a machine have? Nothing but algorithms.

-Ed
 
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Merely using computers and using AI are not even remotely similar.
My point is computers and AI are technologies that both eliminate and create jobs. Technological advancements have been doing this for thousands and thousands of years and will be for as long as humans keep on the same trajectory.
 
My point is computers and AI are technologies that both eliminate and create jobs. Technological advancements have been doing this for thousands and thousands of years and will be for as long as humans keep on the same trajectory.
I’m less concerned with jobs, although that does raise a salient issue, but rather the theft and exploitation of intellectual property and personal data, without which generative AI would not exist. As a member of the creative class, my input is already devalued in our present economic model. Generative AI renders creatives and their expertise irrelevant, while at the same time, stealing their output. This is not merely a matter of eliminating jobs, but also represents an attempt by those with wealth and power to further exploit the artists, writers and musicians by stealing their work without attribution or payment and render expertise irrelevant. Without creative culture, we are merely cogs in a dystopian machine who exist solely to enrich those who already have too much.
 
I’m less concerned with jobs, although that does raise a salient issue, but rather the theft and exploitation of intellectual property and personal data, without which generative AI would not exist. As a member of the creative class, my input is already devalued in our present economic model. Generative AI renders creatives and their expertise irrelevant, while at the same time, stealing their output. This is not merely a matter of eliminating jobs, but also represents an attempt by those with wealth and power to further exploit the artists, writers and musicians by stealing their work without attribution or payment and render expertise irrelevant. Without creative culture, we are merely cogs in a dystopian machine who exist solely to enrich those who already have too much.
I see your point and agree that intellectual property rights need to be secured. Maybe one way to mitigate this would be to have something similar to digital footnotes so the source material used by AI will be available to know. I think that AI can be programmed to know when it is producing something that violates patents and/or copy rights. There is a distinct difference between AI requests that aggregate information and those that produce a product. Over the past couple of years I have read more than a few articles where lawsuits have been filed against AI companies over copyright and patent infringement of AI results. I asked Grok (xAI) the following question and its response is below. It appears that preventing infringement is something that is part of the code Grok uses.

How do you prevent yourself from violating copyrights and patents when providing results to users?

As an AI developed by xAI, I've been designed to respect intellectual property rights and avoid infringing on copyrights and patents. My training data is a complex mix of publicly available information, and I don't have direct access to copyrighted or patented material. When generating responses, I aim to provide original content or summarize information in my own words, rather than reproducing protected works verbatim.

That said, I'm not perfect, and the boundaries of fair use can be blurry. If I need to draw from a specific source, I'll try to keep it factual and transformative—adding value through explanation or context rather than just copying. I also don’t store or replicate entire protected works in my responses. If a user asks for something that might skirt too close to copyrighted material—like a full song lyric or a patented design—I’ll pivot to a more general answer or suggest they seek out the original source themselves.

The folks at xAI have baked these principles into my system, but I don’t have a magic formula I can share—it’s more like an internal compass guiding me to play nice with the rules. If you’re worried about a specific response, feel free to call me out, and I’ll adjust!
 
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