o.k. I bit the bullet when they reduced the price to $295 and the new version can also handle mp3s.
Unfortunately I am not one of those people that can tell you in audio terms why something is better or worse technically, but I believe that I can tell if something material has changed in the sound of my system - for better or worse! Does Amarra Mini jump out at you immediately in terms of sonic improvements? I would say no in my case. But over time ... listening to recordings I am very familiar with...I believe it takes my system up a level in terms of both improved 'bass' (more defined?) and 'space' in the soundstage - but I can't categorically state that it actually does anything. Yes, I tried the demo, and found it useless, as just as I was listening for 'something' - there would be a pause in the music which threw me completely off. Try listening to any classical music that way!
Yes, I confess, I love my Macbook Pro (usb) iTunes/Amarra Mini/Isabellina HPA/ATH-W1000X/Senn. HD650 (Equinox) or AKG 701 ... and (hopefully) soon to come Audeze LCD-2. Whether I made the right decision of ordering the Audeze LCD-2 or not vs the HD800 - only time will tell, but for now, I am really enjoying my HD650s for the first time in this setup.
Cheers!