Looking for good affordable desktop dac/amp with specific requirements, suggestions?

[Adamant11746]

I recently bought a pair of Sennheiser HD 820 (super expensive, but the only closed back headphones that are truly comfortable for me), and I borrowed a 2m cable from a friend who wasn't using it (he has an HD 800s but apparently went back to the longer stock cable). It was terminated in full-size XLR, so I also borrowed an amp from him. The amp is serviceable but not fantastic (Massdrop x Cavalli Tube Hybrid, did not get a good review here), but it did show me just how bad my computer jack is. I'm currently planning to eventually replace it with a solid state amp, and am having trouble finding one with the features I want. I will also replace the borrowed cable at some point, since A) I don't own it, and B) I don't like how bulky the XLR connector is.

I'm looking for the following features in order of priority:

1. Separate power and volume controls (ABSOLUTELY REQUIRED)
2. <1ohm output impedance
3. Either 4.4mm or 3.5mm output option.
4. A built-in USB DAC (not essential but would save desk space)

Everyday usability and long-term reliability are also high priorities. High power output is NOT a priority, provided it's not absolutely anemic. Budget is ideally under $200.

So far I've found:

• FiiO K11 (meets every requirement except 2, at 1.2ohms for 6.35mm and 2.4ohms for 4.4mm outputs, and might be slightly behind other options on ease of use)
• Schiit Magni Unity (meets every requirement but 3, power switch in the back is annoying but probably not a dealbreaker)
• Used Massdrop THX AAA 789 (does everything except 4, limited availability but there are 2 current listings for ~$100 and a couple more that are closer to $150-200)
• SMSL C200/C200 Pro or DL100/DL200 (concerned about reliability and usability, but otherwise meet every requirement)
• Topping A30 Pro or A50 III (extremely concerned about reliability, way more power than I need)
• Moderately powerful dongle and USB hub/extension cord (would work, but I'd rather flip a switch than unplug a USB device when I want to switch to speakers)

I'm currently leaning toward the Fiio K11, Schiit Magni, or the Massdrop THX, but none of them do everything I'm looking for. The Massdrop probably comes closest, but is also a bigger risk because it's used (no warranty) and requires a separate DAC which I have very little desk space for. I'm not in an extreme hurry, but I am somewhat concerned about both of the listings for the Massdrop amp selling before I make a decision.

If I do go for the Massdrop option, I will eventually replace the DAC I'm currently using (SMSL SU-8, borrowed from my father) with something smaller and black rather than silver. I see the SMSL PS100 for $33 on Amazon, or I could go with the SU-1 for $85. I'm not seeing many good and cheap options from non-SMSL companies unfortunately.

 

[DVDdoug]

I won't attempt a recommendation.

but it did show me just how bad my computer jack is.

What's the problem? If you aren't hearing background noise and it goes loud enough there's probably nothing wrong with it. (It's probably better than human hearing.)

<1ohm output impedance

It looks like your headphones are 300 Ohms. The rule-of-thumb is 1/10th of the headphone impedance so 30 Ohms or less should be fine.

Note that sometimes they don't give you that spec... Sometimes they just give the recommended minimum headphone impedance. It's the same with power amps. A power amp rated for 4 or 8 Ohm speakers usually has an output impedance of a fraction of an Ohm but they never put that in the specs. (Sometimes they specify it as damping factor.)

Either 4.4mm or 3.5mm output option.

Balanced headphone outputs (4.4mm) are a gimmick. Typically you can get twice the voltage (6dB louder) with a given amp, but there are easier ways to get twice the voltage, or more.

 

[masterhw]

You either get the RME ADI-2 DAC FS or spend the next while thinking about if you did.
It’s good measuring, but so is everything else. The real selling point is build quality/reliability, long term support, and the powerful in-board DSP. Once you try loudness correction it’s hard to go back.

 

[Adamant11746]

I won't attempt a recommendation.


What's the problem? If you aren't hearing background noise and it goes loud enough there's probably nothing wrong with it. (It's probably better than human hearing.)


It looks like your headphones are 300 Ohms. The rule-of-thumb is 1/10th of the headphone impedance so 30 Ohms or less should be fine.

Note that sometimes they don't give you that spec... Sometimes they just give the recommended minimum headphone impedance. It's the same with power amps. A power amp rated for 4 or 8 Ohm speakers usually has an output impedance of a fraction of an Ohm but they never put that in the specs. (Sometimes they specify it as damping factor.)


Balanced headphone outputs (4.4mm) are a gimmick. Typically you can get twice the voltage (6dB louder) with a given amp, but there are easier ways to get twice the voltage, or more.

The problem with the computer output is likely extremely high output impedance, distortion, or (probably) both. I don't have any data on my particular motherboard, but a different motherboard's output impedance was measured here at 101 ohms (another was measured at 78 ohms).

I also seem to not have given enough information. The HD 820 is 300 ohms nominal, but I also have a Hifiman Ananda Stealth and a couple IEMs (Shure Aonic 4 is the problem, with 7 ohm nominal impedance and a hybrid design). The HD 820 kicked off the realization about the computer output, but I still need to use at least the Ananda sometimes (whenever I need situational awareness) and I might use IEMs if I ever need extreme isolation. I was hoping to unify my outputs for both headphones and IEMs (I currently use a dongle dac for the IEMs, JCally JA3 for the PC and JCally JM12 for mobile).

As for balanced outputs being a gimmick, I know. I wanted either 3.5 or 4.4 because they're smaller and more manageable than the 1/4 inch jack on most headphone amps. Honestly, I'd prefer 3.5 but it's even harder to find than 4.4. My main reason for not using a 3.5 to 6.35 adapter is kind of silly, I just don't like the way they look.

You either get the RME ADI-2 DAC FS or spend the next while thinking about if you did.
It’s good measuring, but so is everything else. The real selling point is build quality/reliability, long term support, and the powerful in-board DSP. Once you try loudness correction it’s hard to go back.

I'd love an RME, but it's unfortunately around 5x my budget.

 

[DVDdoug]

is likely extremely high output impedance, distortion, or (probably) both. I don't have any data on my particular motherboard, but a different motherboard's output impedance was measured here at 101 ohms (another was measured at 78 ohms).

Yes, that could be a problem...

If the impedance is too high there are two related effects - You get a voltage divider with voltage lost across the internal impedance. With a 70 Ohm source impedance and a 7-Ohm load you are loosing about 90% of the signal... About 20dB of reduction!!! Probably way too quiet.

And since headphone impedance isn't constant over the frequency range, the voltage division is different at different frequencies so the impedance variations end-up as frequency response variations.

The signal loss shouldn't be too bad with the HD 820 (only a few dB) and you didn't say it was too quiet. And the frequency response variation shouldn't be too bad either, but it won't be "as measured" or "as specified". I looked at the review here and the impedance is a little higher lower frequencies so you can expect a slight relative bass-boost with a high impedance source. And the impedance is a little lower in the higher frequencies so you'd get a slight drop in the higher frequencies. ...The frequency response of the HD 820 isn't that great to begin with so wouldn't want to make it worse.

With a low-impedance source, you avoid all of that.

I've never heard distortion from ANYTHING that wasn't broken or overdriven. Soundcards and DACs are designed with analog headroom that's higher than the digital maximum (0dBFS) so they are impossible to overdrive. You can clip the digital data before it gets to the DAC if you are using EQ to boost the digital level but unless it's badly designed you can't clip the analog output.

If you have a separate headphone amp with an analog volume control, it's not "calibrated" to the DAC and you can usually turn up the knob and push it into clipping/distortion.

 

[Adamant11746]

I'm leaning more and more towards the Schiit Magni Unity. I will likely just have to deal with the ugly adapter on the rare occasion I use my IEMs (and the Ananda, which I chose a 3.5mm cable for) at the desk. The FiiO K11 is out of contention because I read the instructions and turning it off requires holding the knob down for 5 full seconds. I'd rather deal with a power switch on the back than that. The Massdrop THX AAA 789 might still be a possibility, and is the only option with a 3.5mm output, but I don't really have much space for a DAC on my desk (and the pressure of used availability means I can't wait as long).