Apogee Groove DAC USB thumb drive at £210 just the ting for me.
Specs
https://apogeedigital.com/products/groo ... ifications
Powers upto 600 Ohm headphones.
Drives my 250 Ohm Beyer Dt880 pro to ear damaging levels lol.
It's supposed to be fairly neutral.
Chunky little chocolate bar lol.
Soft volume buttons with light up indicators.
Just 3.5mm headphone out and single micro USB port with detachable cable powers directly from USB2 USB3 USBC on computer.
Mac is plug and play even on my 10 year older 10.6.8 Snow Leopard.
Windows 10 requires driver download after registering.
Test Headphones

35 Ohm to 470 Ohm (Om Shanti, Om Ma Ni Padme Hum).
470 Ohm Audio Technica R70x open back.
250 Ohm Beyer Dynamic Dt880 pro open back.
062 Ohm Akg K702 open back.
035 Ohm Philips X2hr open back.
Subjective listening observations
Scenario : Mixing my music in home personal studio.
Music styles :
My pseudo Orchestral, pseudo Choral, pseudo Jazz, pseudo World, Rock, Acoustic, Electronic, some heavy Bass tracks.
Compared to :
Akai EiE pro 24bit.
On 2010 Macbook.
Apogee Groove is an improvement over my Akai EiE pro headphone out for:
Clarity, detail, definition, depth, separation, spaciousness, reverb tails, transients, how everything sits together in the mix;
Bass increased definition, depth, tightness, Bass heavy tracks I could feel the rumble nicely;
Mids just the amount of body fullnes for my preferences that is not overly full;
Highs a trifle sparkly (without harshness, shrillness).
Relaxed, cruise control sound.
Groove is staying, EiE pro is departing.
(Recently I had Audient id4 mk1 and Focusrite Saffire pro 24, I preferred Akai EiE pro headphone out to them).
Neutrality, Distortion
Please don't ask for graphs, measurements. I might run and hide if you do lol.
I can say the Apogee Groove is sufficiently neutral for my current requirements.
My mixes translated alright onto Akg k702, Audio Technica R70x, Beyer DT880 pro, Philips X2hr, each with their different signature sound.
As volume is increased my ears couldn't pick out any distortion.
As volume is increased Bass Mids Highs remained consistent as far as I could tell.
Drawbacks
No balanced out.
Micro USB port on the Apogee. Would preferred USB C.
No digital volume display, it's a bit hit and miss with the volume pads.
Similar alternatives
Haven't tested these, don't know how they perform.
Going by youtube reviews, comments.
*Audioquest Dragonfly Cobalt
https://www.audioquest.com/dacs/dragonf ... fly-cobalt
*FiiO Q3 https://www.fiio.com/q3
*Ifi Hip DAC https://ifi-audio.com/products/hip-dac/
*Motu M2 and Focusrite Clarett 2Pre
according to Julian Krause's testings https://m.youtube.com/c/JulianKrause/videos
Focusrite Clarett 2Pre headphone out, performs rather well with high impedance headphones.
Motu M2 has better quality headphone out upto 300 Ohms compared to other £100-£200 audio boxes as SSL S2, Uad Volt, Audient id4 mk2 id14mk2, Focusrite Scarlett gen3.
I will follow up when I can.
Summary
Apogee Groove is a viable alternative to £100-£400 audio cards headphone out, when just headphone out is required. Particularly for high impedance headphones upto 600 Ohm.