The sound of these things really does seem quite good, I have a 3255 based amp and I would have to get quite nitpicky to find much fault with it. My previous experience with class D was from a TPA3116 based cheapie from 10+ years ago, it was a prebuilt cheap amp but one that was somewhat raved about here on the forums as I recall it. Once you got over the "wow this tiny box actually puts out enough power for regular listening and sounds quite OK doing it" it was not a good amp even after upgrading some of the cheap caps etc. I maybe used it for about 2 weeks after which it has sat in a drawer waiting for the occasion I might need a tiny amp somewhere.
Anyway things really have moved on from that time it seems. The 3255 amp is not up to the level of my Class A/B reference, but then again that amp weighs like 30kgs and if I could buy it new, it would cost at least 10 times more than these cheap class D amps, probably more. Putting the class D amp against other amps that also failed against that reference, there's practically nothing in it and I wouldn't be surprised if the $100 class D amp actually came on top in comparisons if differences could be detected at all. I can also think of many amps that performed clearly worse.
On the negative side some of the value is a bit misleading and sometimes I feel like people judge these things to a different standard because they are so cheap, overlooking any little nagging issues they might have. Also many of these things offer barely any features, yet people regularly seem to compare them to integrated amps which also have a preamp, ton of inputs, a phono stage etc... if you get all that from these cheap boxes, suddenly you have a stack of them and the price difference to an "old brand" integrated is no longer quite as big and you have to manage the mess of cables and SMPS power bricks. I mean the amount of cables is not really any different to old school separates but the very tiny boxes that have barely adequate room to hold tightly spaced connectors doesn't make things easier, plus some of these things are so light they might not be able to resist the pull of cables.
Anyway they have seemed to reach a certain level of maturity.There are still some "issues" though, like some of these amps do stupid things to get fractionally better SINAD figures or whatever so that they seem more impressive in tests on one particular audio forum, or just out of sheer ignorance. I almost pulled the trigger on a Topping Mini 300 because it really seemed like a great little amp but luckily I didn't, because I later found out the input impedance for the RCAs is 1kOhm... that is so unacceptably low it's insanity. Input/output impedance of solid state gear used to be something you didn't really have to worry about, you could safely assume the output impedance was low and the input impedance was like 10kOhm at worst but more likely in the 20-100k range. That seems to no longer be the case, but I'm sure these companies will listen if people actually speak up about this issue. For some people it might not matter, especially if you are putting together a system from scratch and are aware of the issue, but how many people really are aware of it? The Topping Mini 300 is the worst offender I'm aware of, but that really is quite bad. I have a phono stage which doesn't have anything weird in it's design, but it expects to see minimum of 10k impedance at the next stage, which is simply not an issue with vast majority of amplifiers in existence. With the Topping it would have a -3dB point at 70Hz or something. Even many CD-players etc. could have issues with that low impedance. Heck you could buy a Mini 300 and Fosi P4 thinking you are putting together a great budget system out of recommended components and have 1:1 impedance between the pre- and poweramp. There's a lot of issues that can come with that. Even if it ends up working sort of ok, it's always going to be far from ideal.
Probably the best thing about class D is the effeciency and it has really made me think about the sensibility of my old amp... even though I like my old mosfet beast better, the difference is not that huge and judging from the amount of heat it produces, it probably draws something like 200 watts or maybe more just sitting idle and for it's rated power output we are talking well over 1kW. During winter time that's not really an issue unless the price of electricity happens to be very high, but you can bet I won't be firing that thing up during summer months unless the weather is particularly cool... These class D amps OTOH typically idle at something like 10 watts and the power difference between what you put in and what you get out is not that much at all.
Have you ever seen an amp that actually do what the specs say? Not many of them no matter where they are made. I think it would be better that you keep on your lane and enjoy the vintage stuff and let others enjoy their Class D amps.
You know, it's not actually rare at all for amps to do what the specs say. In fact a lot of older (quality) gear when tested would often surpass their rated power figures. At the budget end probably not.
Also it used to be if an amp claimed 0.005% THD and 100W into 8 ohms, that meant it would do that 100W with no more than 0.005% THD. Now many these class D claim something like 0.002% THD, but that's at 5W or something and max power is at 1% THD. Either the THD or power rating would be very different if they were not cherry picked like that. On the positive side the manufacturers sometimes provide actual measurements which tell the full(er) story.
The "300+300W" and other crazy numbers are easy to just ignore and manufacturers of old also did this with some vague, non-standardized power claims. Most companies seem to provide a chart which shows the available power brick options and a realistic max output power with each option, though at some point I bet cooling would become an issue. I have my doubts a palm sized amp with only the tiny chassis acting as heatsink can put out 200+200W for any length of time before thermal protection kicks in.
If anything it's a testament of overall sound quality these have reached that people are starting to treat them with same standards as "classic gear" and not just gloss over any issue with "but it's so small and cheap".
neuralink.com
