Replacement arrived, hooked up (via optical). Only played a few hours, but I can say both as an amplifier and a DAC it is pretty phenomenal.
Bearing in mind the unit has only a few hours running and has spent 16 years in a box I am impressed. The DAC on 16/44 material matches by Buffalo 3, in fact I think it drags more out of the mix than the Buffalo. Depth, spacial information and sheer speed seem better. There is perhaps a hint of harshness that isn't there on the Buffalo, however that could just be the fact that its more accurate. This is feeding the JVC from a Mac via a M2 Tech Evo with external clock and power supply and with an optical SPDIF.
The amp itself if just as impressive, fast and detailed. The bottom end is getting more full as the unit burns in, what is impressive is the control it has over the music, I have never heard as much separation between instruments even during complex passages. As flatpopely says, it seems to reveal elements in the mix not noticed before.
Needless to say I am impressed. We certainly didn't give these monster Japanese amps a fair chance in the '80's and '90's as everyone was smitten by the Naim / Linn party line.
As a final note, the seller has been amazing, sending out a new unit right away even before I sent the old one back.
More later once I have tried hooking up via coax and trying the phono stage.