I’d never use anything UAD again, after their attitude to me with a faulty OX-box.
Piece of junk.
Their lethargy in updating drivers for Mac OS is pitiful.
The Motu M4 is a good unit, although the ESS Sabre chips are a bit forward, but that’s ok.
For headphones like Beyer DT, or Sennheisers- you should really have a quality headphone amp, like the Beyer A20.
(The HD600 and A20 is an incredible match, and the A20 makes DT880’s sound much better than they should)
My Bryston BP6 pre-amp has great output on headphones. My Motu M4 does not. You’d think that you might be able to live with it maybe?
But the M4 was weedy and thin. The Bryston was much fuller and authorative.
But adding a Beyer A20 amp, showed that all along in both, there had been a hole in the middle of the image, and that panning on headphones would have been impossible to implement accurately without it.
The newer RME API Pro has a very good dedicated headphone amp, but is £1500.
For that money, I would want varied digital connectivity, like S/PDIF and AES/ABU, together with USB.
Too expensive for most people, even though it has good AKM chips and useful DSP.
I bought a Bryston BDA-2 DAC and now output to that from my Mac. It has the AKM chips like the API.
So I have reverted back to my older Motu Ultralight mk3 for inputting audio, on which I use the S/PDIF out straight to the Bryston DAC’s converters. Latency is still 1.1ms at 96Khz with 128 samples, with a Mac Mini M4.
The Motu M4 requires a USB2 audio cable, with USB-C connectors. Not a Thunderbolt cable.
Best audio bargain is the standard Supra USB-C 1.5m, at £40. Nice balanced sound.
I do use a £300 DH LABS Mirage 1.5m USB-C to USB-B cable from Mac to Bryston DAC direct - and really love it. But then my reference system is capable of showing up the minute differences.
With the Ultralight mk3 S/PDIF into the Bryston DAC, using a Van Damme copper 3m S/PDIF cable, I sense a tiny bit of smearing on busy hi-hats occasionally. Not so with the DH Labs cable and straight USB connection.
If you can live without digital connectivity - the Motu M4 and a Beyer A20 headphone amp is the bare minimum for decent DAW audio-input, and a decent level of monitoring.
The Bryston BDA-2 has a wonderfully transparent sound, like all their gear. But it is implemented to be slightly laid-back in it’s converters. This is really great when manipulating subtle space and depth in mixes.
The more forward ESS Sabre chipped DACs, tend to not allow for such nuance.
The RME API is forward, even with its AKM chips, and for anyone mainly composing and mixing in DAW, I would definitely recommend buying a Bryston BDA-2, and using a lesser ADC as an input device for analogue to DAW.