As at Feb 2012 I still believe that upsampling to 384Khz and higher has real benefit . Most dacs are only able to process 192Khz and the benefits of upsampling aren't as obvious at this frequency imo. The Sabre 32 bit dacs are my choice of dac chip and play superbly at 384Khz using either JRMC with windows7 or PureMusic and Audivarna Plus with macs.
To enable usb playback at 384Khz I've been using the EXAdevices U2I usb-i2s convertor into a Buffalo2 Sabre dac, and I've commisioned AckoDac to build me complete units of the EXA U2I device integrated with their best Sabre based dac.
This will be used with a E280F tube output stage incorporating 12B4A shunt regulators, Magnequest iron, lowR bias and many of the special Supratek tube tricks. Completion end Feb 2012, not planned as a Supratek product, but just for myself and a couple of friends.
In the meantime I've brought the first EXAdevices E18 dac into Australia. This is a USB 32 bit/384Khz capable 8 channel dac www.exasound.com/e18DAC/Overview.aspx
However I'm using it with the opamps and filter disconnected and instead of all 8 outputs paralleled for 2 channel stereo operation I'm just using two of the outputs into one of my tube I/V output stages. This is for stereo use, this dac would also be ideal for active crossovers using multi outputs.
Apart from being a very good looking dac with it's CNC milled front panel, used with a tube output stage, it's the best dac i've heard so far, very detailed but beautifully toned and very atmospheric, the room acoustics of the recording studio or venue are very obvious with this dac, spatial depth is very obvious and it has a uncanny sense of 3D imaging.
The best of todays digital products have none of the "digititus" of the 90's and 00's products and the EXA E18 is very transperant and misses nothing yet is still very engaging and toe-tapping to listen to.
I'm hopeful the EXA/AckoDac/Supratek will be better, but if it is a good as the E18 with tube output stage I will be happy. Note I can not comment on the EXA E18 with standard opamp stage as i haven't heard it, but I suspect it would beat anything at or well beyond its price range.
