Hey ID,
I'm giving it a bit of a listen now. It's nice that I can carry something of this quality around with my laptop. so far I have been impressed by the soundstage and clarity of detail. It's a little on the cold side, but I think that is a bit of a Fostex thing. The HP-A8 is like it too. It's not horrible, it's really personaly preference, but although it's not quite for me there is a lot here to appreciate.
I love the metal volume dial and build is stunning! The connections are cool (digial out, RCA line-out), but I'm not convinced about having an optical input with a USB powered unit, that seems complicated.
I will be playing with the HP-A8 and TH900 headphones mostly first (as they have to go back soon). In the mean time here is a pic I just took of all the Fostex gear I am playing with...
http://noblehifi.blogspot.co.uk/2012/10/fostex-flood-coming-soon.html
Oh and rather weirdly the default driver that Win7 installs for the Fostex HP-A3 only accepts 96khz (don't know if there is another driver or if this is a rule for the HP-A3). Windows itself just upsamples everything, but with Foobar and Jriver it's a bit more tricky as it has to me manually changed if you're using WASAPI. I've had one DAC that wouldn't take the standard CD bit-rate (had to be up-scaled to 24bit), but this is the first time the sample rate has needed to be up-scaled.