My A4 just landed today from Moon Audio. I have it running in now with my LCD-2s. I'm running it from my Windows 8 desktop with the nice white USB cable provided, and I am using the Fostex software player (don't have anything but iTunes setup on this machine). I haven't had a 'real' headphone setup in a long time, so I can't give any valid impressions of sonics or how well it drives the LCD-2. Drew at Moon Audio said that it drives the LCD-2 well though.
It is well made, and yes, it took a while to find the Windows USB driver, since it's not on the A4 page. No hiccups here. Sound is smooth and rich through the headphones, and even through my Acoustic Energy Speakers I use.
The software player has a cool Fostex look to it, not a lot of functionality though. I think I heard a difference when I used the player, but I haven't done any comparisons to iTunes yet. Has anybody dones any player comparisons between the Fostex player and other contenders?
I have a Macbook Pro, and I will probably try that out as well.