Thanks to Alex who is kindly loaning me this amp for my auditioning. I received the A.N.T. Amber yesterday, and have been listening to it since first thing this morning, and I've been listening to it for a few hours and have formed some impressions. First things first, the appearance of the amp is one of no-nonsense design, solidly built, but nothing flashy really - it could quite easily be any other DIY design to look at. To be honest, after my past history of headphone amps, I wasnt really expecting a great deal to be honest, but as this is my only method of listening from now on I must have a headphone amp. The Amber is the interface between my EMU 0404 soundcard and my Beyerdynamic DT531 headphones. Let me just say, that after listening to various music for the last few hours, this is a wonderful combo. The first thing that surprises me is the bass - I am used to hearing weak, lifeless bass from most headphone amps, but not so with this one, which is clearly up there, or even better than my integrated amp was in terms of sheer quantity, but its the quality of the bass that is winning me over so far. The DT531 can have quite soft bass if not driven properly, lacking in conviction. With the Amber powering these cans, the bass slams hard, and is perfectly agile and well timed, with a fast bass that responds to every change immediately. Not only is the bass well timed, but so is the rest of the music, and this gives it a really fun sound to listen to, this is an amp you flat earthers will love, its just so musical There is plenty of detail here, more than I've ever heard in the past, but this is no analytical amp, its certainly not what I would call a cold amp, it definitely has some nice warmth to its sound, but make no mistake, this isnt like a Perreaux, this has an upfront sound that injects life and vitality into the music. Surprisingly for an amp with so much detail, it never sounds ragged or rough, it always sounds very smooth - my biggest surprise is bad recordings - for the first time, I can listen to some recordings without wincing. Yet nothing is rolled off, the treble is all there. This thing also throws out a big soundstage, possibly one of the biggest I've yet heard on these DT531's. The Amber certainly looks like being the final piece in the jigsaw, and I have to say, with it in the system, this rig I am listening to easily qualifies as the most lively, engaging, and just plain fun headphone combination I have EVER heard. Considering I was expecting little, I am finding myself VERY surprised at what I am hearing on this rig - its dynamic, detailed, smooth, engaging and it really, really boogies! There is no sign of the harsh treble that can sometimes affect the DT531 with many amps, which was my main worry, but make no mistake this is a very clear and extended sounding amplifier. I can imagine it being a wonderful amp for Sennheisers and Beyerdynamics, but I cant comment on Grado's... perhaps with those it might be too much of a good thing, but I dunno, but for slightly more laid back headphones, if you need energy pumping into them, this is a good amp to do it with!