Best portable USB bus powered headphone amp

[lsanbourne]

Hello, I'm a classical audio engineer, often mixing audio on the go with headphones, with very minimal suitcase space (EU<->US travel).

Can someone recommend a USB bus powered headphone amp that I could use on the go, unlimited budget, and would sound as good as Grace m108 headphone out? Bonus points if it has balanced outputs and thus could double as a monitor controller at home.

Current recording setup: 8 Schoeps mics -> Grace m108 -> listening with HD600
Current home studio: RME UFX III -> 2 Neumann KH 120
Current hifi system: Cambridge Audio, Revel, fed by RME ADI 2, WiiM hockey puck that doubles as a streamer

I heard good things about JDS Element III, Fiio K9, Schiit Jotunheim, and iFi GO Kensei, but the formers don't have USB bus power (and often aren't even dual voltage), and the latter brand doesn't do well in ASR tests.

I considered Neumann MT 48 but have heard that the signal path design is not exceptional.

I'm open to spending whatever it takes!

Thanks again,
Larry

 

[staticV3]

Bus powered with Balanced Line out + Headphone out:

• Topping E1x2/E2x2
• Khadas Tone2 Pro

 

[lsanbourne]

Thanks, staticV3! How would you expect those to compare to something like Grace m108 or Grace m900? I'm skeptical that something so much cheaper would actually be superior.

 

[staticV3]

Thanks, staticV3! How would you expect those to compare to something like Grace m108 or Grace m900? I'm skeptical that something so much cheaper would actually be superior.

Both the Khadas and Topping are fully transparent DAC+Amps, which means in this regard (noise, distortion, linearity) they cannot meaningfully be bested no matter the price or heritage.

If the hundreds of reviews by Amir have taught us one thing, then it's that in audio, price and quality are rarely correlated.

 

[lsanbourne]

Thanks. Is there a page on the site where I can see how m108, m900, Topping E*x2, Khadas Tone2 Pro, Babyface, and UFX III score on the most important metrics?

I ask partly because Babyface is no slouch on the measurements (according to its ASR review), but I am finding it astronomically easier to mix with m108's headphone out than Babyface's. There's obvious stuff like stereo imaging being more precise, but also my ears are much better able to parse out fine details of reverb with m108's headphone out. So I'd like to learn where Babyface sits in the rankings and make sure I get a monitor controller (and the portable headphone amp at hand) that best it.

 

[mcochris]

I considered Neumann MT 48 but have heard that the signal path design is not exceptional.

That’s interesting, do you have a source for that?

 

[lsanbourne]

That’s interesting, do you have a source for that?

It came from the founder of a major mic preamp company that does not themselves sell a competing product. But I haven't asked for permission to post the name publicly, sorry for the mystery!!!

 

[staticV3]

Is there a page on the site where I can see how m108, m900, Topping E*x2, Khadas Tone2 Pro, Babyface, and UFX III score on the most important metrics?

Here it is:


Enable Titles only and Posted by: amirm and you'll find his review of the E2x2, Tone2, Grace M900, and RME Babyface.

 

[lsanbourne]

I was looking for rankings of all devices according to all the measurements…I have already read the reviews.

 

[solderdude]

Hello, I'm a classical audio engineer, often mixing audio on the go with headphones, with very minimal suitcase space (EU<->US travel).

Can someone recommend a USB bus powered headphone amp that I could use on the go, unlimited budget, and would sound as good as Grace m108 headphone out? Bonus points if it has balanced outputs and thus could double as a monitor controller at home.

Current recording setup: 8 Schoeps mics -> Grace m108 -> listening with HD600
Current home studio: RME UFX III -> 2 Neumann KH 120
Current hifi system: Cambridge Audio, Revel, fed by RME ADI 2, WiiM hockey puck that doubles as a streamer

I heard good things about JDS Element III, Fiio K9, Schiit Jotunheim, and iFi GO Kensei, but the formers don't have USB bus power (and often aren't even dual voltage), and the latter brand doesn't do well in ASR tests.

I considered Neumann MT 48 but have heard that the signal path design is not exceptional.

I'm open to spending whatever it takes!

Thanks again,
Larry

Why not use a battery powered headphone amp that you simply connect to the headphone out of any sound card ?

 

[lsanbourne]

My Macbook's sound card sounds bad, so I want something that replaces that. interface+DAC+headphone amp, bus powered.

 

[solderdude]

Topping E2X2 but is only USB-C because of the power drawn.
Perfectly able to drive HD600.

 

[staticV3]

@lsanbourne
If you only need a single mic input, then the E1x2 is worth considering as well.

It has the same DAC, ADC, and Headphone Amp as the E2x2.

 

[scolfaro]

Thanks. Is there a page on the site where I can see how m108, m900, Topping E*x2, Khadas Tone2 Pro, Babyface, and UFX III score on the most important metrics?

I ask partly because Babyface is no slouch on the measurements (according to its ASR review), but I am finding it astronomically easier to mix with m108's headphone out than Babyface's. There's obvious stuff like stereo imaging being more precise, but also my ears are much better able to parse out fine details of reverb with m108's headphone out. So I'd like to learn where Babyface sits in the rankings and make sure I get a monitor controller (and the portable headphone amp at hand) that best it.

Headphone outs in the Babyface Pro FS (which is my mobile interface) are SEVERELY underpowered, I also had troubles for a while, but realized how my other headphones (especially the Sundara which is similarly sensitive with the HD 600) behaved in the UCX-2 or ADI 2 FS in comparison. It was like a new set of headphones. So forget about using them for anything that needs current, the UCX-2 is the lowest you can go as far as mW per channel (240). The Babyface Pro FS only puts out 90mW. This isn't related to loudness, but also how much current it can deliver to the cans, and that is just too little to get the headphones to sound like they should.

 

[staticV3]

This isn't related to loudness, but also how much current it can deliver to the cans, and that is just too little to get the headphones to sound like they should.

So current affects the sound quality, but is not related to loudness? How is that supposed to work?

 

[scolfaro]

So current affects the sound quality, but is not related to loudness? How is that supposed to work?

I meant that this isn't related to how loud you're listening. Not to how loud they can go. Irrespective of listening levels, even if you're listening at very quiet levels (which is common among audio engineers while mixing for long hours), headphones won't sound as they should. If you try to turn it up, you'll probably notice you can't, but to someone mixing on them (as was the case with me) I assume you won't go to painful levels and won't realise how inaccurate the headphones are performing on them.

 

[scolfaro]

Probably should have said "this isn't related to listening levels"...

 

[staticV3]

Irrespective of listening levels, even if you're listening at very quiet levels (which is common among audio engineers while mixing for long hours), headphones won't sound as they should.

I'm not aware of any mechanism by which a headphone amp could do that.

Could you please elaborate?

 

[scolfaro]

I'm not aware of any mechanism by which a headphone amp could do that.

Could you please elaborate?

I'll speak from experience, which is probably not enough on a forum where everyone is measuring everything, but there's a great deal of subjectivity in audio work anyway, so take it as you wish.

The Sundaras, for example, -can- be powered by a cellphone. But there is an obvious difference when being fed by anything capable of delivering above 200mW per channel, and they sound the -best- when I run them balanced through an amp capable of delivering 1.1W per channel.

Bass transients are the most obvious difference, they sound "soft" or not textured on the Babyface Pro FS (which would probably cause you to react by increasing kick drum levels), and seem to pick up "speed" when given enough power, significantly more punchy in general. There is a huge rift in that department between Sundaras and the Audeze LCD-2 that gets closed by a great margin once enough power is fed to the Sundaras. The Audeze OTOH seem to thrive even on the measly 90mW from the Babyface. This is absolutely related to their sensitivity.

The general impression was of "clearing up", as if a veil had been lifted through the spectrum. ATH m50x and other higher sensitivity headphones showed no difference at all. So to close my opening arguments, Sundaras "can be powered by a cellphone", but that doesn't mean they will sound like they should. I am absolutely sure this is measurable, I don't think anyone did (how crappy headphones with low-ish sensitivity can sound when underpowered). Everyone cranks up the volume and states "they can't get loud enough on this amp", but no one compares them at low-level.

 

[staticV3]

I am absolutely sure this is measurable, I don't think anyone did

Strange.

One'd think that, in the last century of Amplifier design, someone must surely have picked up on this real, measurable effect.

And yet, nothing.