What are the main reasons for getting a headphone amp?

[Alobar]

Here is the schematic for the headphone amp on my Kenwood 700C preamp. I really get lost on a lot of this stuff as to the how's and why's, but maybe someone can tell me if this looks like a decent and stand alone headphone amp.

 

[elcoholic]

It looks promising. I'd say it's a complete amp. Way more than an L-pad for sure.

 

[Bob]

excellent - the headphone block is a discrete implementation of what vendors will use an opamp IC for
if they don't just tap the power amp outputs.

 

[FileFixer]

One reason to have a headphone amp would be for a stereo system in a location where you would would not be able to or would not want to play music over speakers.

The ideal quiet-room mini-system:
1) A music source (cdp, tape deck, tuner, etc.)
2) Headphone amp
2) Headphones

Alternate version:
1) Turntable
2) Mini phono preamp
3) Headphone amp
4) Headphones

This is my ideal setup for quiet room system and loud also. Everywhere, wherever...

 

[Alobar]

So I have a partial solution to help determine if I will require a headphone amp other than what is in my Kenwood. I ordered a FiiO DAC/amp which while wasn't purchased for my home use, may give me a point of comparison. This model can bypass the DAC and just use the amplifier (RCA in and out) so if there is any improvement from my Kenny pre, it will probably take me to further upgrade to a home use table top headphone amp later on. Couldn't find actual output data for the FiiO amp section, but it claims to work well for headphones down to 30 ohm on up to 300. This was bought for the purpose of playing FLAC/APE files from my cellphone while away from home so a much different purpose from listening at home through my DAC and source.
FiiO Q1

 

[olderroust]

Thanks for the info, and great link! I learned a lot.. I dug out the owners manual for my old Kenwood 700C and discovered it has an 8 Ohm phone output, a little higher than what would be max for 50 ohm cans using the 8ths rule, so will be looking for a headphone amp for in home use.

That's a very good output impedance - definitely in the range of where headphone amps are.

The thing that continues to amaze me is that so few reviewers seem to understand why the number might matter. It's not a difficult number to measure for yourself - a decent measurement can be had for the cost of a 50 ohm dummy load and a multimeter, a better one simply involves adding an oscilloscope (a cheap USB oscilloscope will do just fine for this measurement.)

The Fiio you have is reported to have an output impedance of less than 1 ohm, so it should be able to let you hear if the Kenwood isn't well matched, but it may well be fine on its own with the Senns.

Sometimes you'll see a reviewer commenting on the sound of a high impedance headphone amp while using low impedance cans. I've seen reviews of 60 ohm output headphone stages conducted entirely with cans in the 30-50 ohm impedance range - the reviewer wasn't ever listening to the headphone amp as much as to the impedance curves of the headphones in use!

 

[elcoholic]

So I have a partial solution to help determine if I will require a headphone amp other than what is in my Kenwood. I ordered a FiiO DAC/amp which while wasn't purchased for my home use, may give me a point of comparison. This model can bypass the DAC and just use the amplifier (RCA in and out) so if there is any improvement from my Kenny pre, it will probably take me to further upgrade to a home use table top headphone amp later on. Couldn't find actual output data for the FiiO amp section, but it claims to work well for headphones down to 30 ohm on up to 300. This was bought for the purpose of playing FLAC/APE files from my cellphone while away from home so a much different purpose from listening at home through my DAC and source.
FiiO Q1

I have a Q1 as well. I use it with my AKG K240’s. I don’t notice a big improvement over my MacBook Pro’s excellent sound card. On the other hand it was a huge improvement over my work HP laptop. I also note significant improvement with my iPods using a line out adapter.

 

[Alobar]

So my FiiO Q1 showed up today, a day early along with the Sennheiser HD 579's and all I can say is wow! I love these cans!

More to the point of this thread, I have been listening mostly through the FiiO (analog in and out) from the Kenwood preamp as well as playing through the Kenwood headphone amp and it is a tough call as to which sounds different, let alone better. It is possible that the Kenwood headphone amp is heard a slight bit more in the bass dept which would go along with the fact that it is a 8 ohm and the Sennheiser's are 50 ohm. The difference is slight however.

I think eventually after allowing my audio budget to recover I will look at a headphone amp. Right now I'm just enjoying these new headphones!

 

[keilau]

I am fairly new to the world of headphones. I have just ordered the Sennheiser HD 579 which are a 50 ohm, open back model and I probably won't play these too loud. I have a rebuilt Kenwood vintage separate amp/preamp now, each with headphone jacks. I know this will probably be a difficult question to answer, but is there an advantage to buying a separate headphone amp for these cans? I am looking at the Schiit Magni 3 as in my budget range, but I obviously don't want to buy it if the Kenwood 700 headphone amp will be just as good.

Having such little experience with headphones I probably wont ever be certain if I am hearing the HD 579's at their best without understanding just what a separate headphone amp can do for me.

The Kenwood 700C with the Sennheiser HD 579 seem to be compatible. The low plus/minus 5 volts rail voltage of the 700C headphone amp could have been an issue for higher impedance phone, but, hopefully, not the 50 ohms HD579.​

When I listen to headphone, the 2 important factors are:
(1) Long session comfort which means light weight and open sound.
(2) A 3 dimensional sound stage which will not make the music 2 dimensional or all in the head.

Many power amplifier or receiver do not have dedicated headphone amp circuit. They use a padding resistor of a few hundred ohms to tap the speaker output for the headphone jack. The headphone needs only milli-watt of power, the padding resistor is necessary for the user not to hear the noise. As a result, the output jack has plenty of driving power, but gets very poor transient response and no sound staging. This is not a problem for Kenwood 700C with the Sennheiser HD 579. You need to do a comparison yourself to know the difference. If the Schiit Magni 3 headamp sounds no difference to you, then use whatever is the cheaper approach.

To me, the depth of sound stage is particularly important in headphone listening. It needs a good phone and a good amp to bring it out. Otherwise, the music becomes 2 dimensional.

 

[Alobar]

To me, the depth of sound stage is particularly important in headphone listening. It needs a good phone and a good amp to bring it out. Otherwise, the music becomes 2 dimensional.

As I play the HD 579's with my 700C I have been getting sort of a revelation it seems! I have never really heard this sort of detail, and 3D imaging from HP's as with this combo. (Granted I don't often get the chance to audition headphones due to the remote location I live in). The bass, not overemphasized (running tone controls flat with loudness off) but detailed in a way that my Bluetooth headphones are not. Muddy is what I have been getting till now in that low frequency range. The Senn's have even got me thinking about replacing my beloved JBL L200's (that I have owned for 44 years) at some point with something modern that will give me an improved 3D image like the 579's for my living room. It is a little intoxicating really... Makes me wonder what the more expensive headphones are like..

As for the headphone amp, I am just going to hold the money, at least for now. I suspect that there could be gains with a more expensive HP amp but that is a rabbit hole I am going to avoid for now, especially with only very minute differences with the FiiO Q1 and the internal 700C HP amp.

 

[keilau]

As I play the HD 579's with my 700C I have been getting sort of a revelation it seems! I have never really heard this sort of detail, and 3D imaging from HP's as with this combo.

As for the headphone amp, I am just going to hold the money, at least for now. I suspect that there could be gains with a more expensive HP amp but that is a rabbit hole I am going to avoid for now, especially with only very minute differences with the FiiO Q1 and the internal 700C HP amp.

Congratulation, the Sennheiser HD579 is supposed to be one of the best value in headphone and you get a well matched headamp. It offers the natural sounding bass with a flat response. I have the HD598 and the HD600 from the same family. Stick with what you have until you are itching for improvement.

The FiiO Q1 is for portable application. Yes, there could be gains with an AC powered HP amp but the limitation will then be in the headphone itself.

 

[Alobar]

The FiiO Q1 is for portable application. Yes, there could be gains with an AC powered HP amp but the limitation will then be in the headphone itself.

Yes, I agree on the FiiO being for mobile/portable use which is what I bought it for, being away from my home rig. I have a cellphone dedicated to file storage with a 200GB chip in it and lossless files.

What my comparing with the Q1 and the 700C was about was simply to determine if I could hear any frequency peaks due to its 8 ohm output on the Kenwood versus the very low, less than 2 ohm on the FiiO. It would seem that the higher impedance on the 700 is having a negligible effect on the 579's.

 

[Judas Priest]

I bought and built my O2 just to be sure that I am getting the best out of my headphones.

By that I mean that the amp is capable of driving them properly at all frequencies.

 

[2channel*]

Or (1+4)/2=2.5 I do have Stax e'stats and drove them off my main system's tube amp on the 8 ohm tap. Meanwhile my Bi-wired B&O speakers were on the 4 ohm terminals necessitating pulling 4 sets of banana plugs at the speakers to listen to the Stax. So eventually I bought a Musical Fidelity V90 speaker amp to feed the Stax 230 Volt output adapter for the Stax "ear speakers". Totally worth it by the way.

I got a Topping T30 for exactly the same reason. It is a great bargain; but now I'm looking for something a bit better. (Quite a bit) I'm looking at a few options; but the V90 is no longer available new and had no conventional headphone jack. Does anyone else have any other good suggestions? It would need to have RCA inputs and speaker outputs, of course, for the Stax adapter/driver.

 

[J English]

Does anyone on this thread have a Schiit Magni 3 yet? Interested in impressions/comments. I am hoping to get one of those in the near term for use down in my work (cube) setup. I'm currently using a NAD 1020 as my headphone amp connected to CD and tape. I have a number of dac/amp combos and a couple of inexpensive standalone dacs, I would probably sell one or two of the combo ones and keep my better dac with RCA outputs to go into the Magni. I like that the Magni can be used both as a general system preamp to add gain, but with a really low noise floor, as well as a headphone amp.