I pretty much enjoy the sound coming of this, I totally need to get a better dac tho, thinking of smsl 10th... anyways while listening from my xduoo x10 to 24/192 vinyl rips it sounds really good! dont expect full, lamp driven amp, its only the preamplification run on theese to give you the nice warmth, the main amplification is done with transistors. On v-moda m100 (32ohms) The volume knob stays in lower 1/4, I dont think you would need more than a half volume for 600ohm headphones tho... 700mW is extremely powerfull. For 80usd discounted, I couldnt ask for more!
If you can, get youself one of theese, just avoid these with non liner power supplies (the big box on back = good)