DAC for Solo UL and HD650?

On a PC, higher resolution bitrates such as 24/96 will require specialised drivers (at least under XP) as the generic USB audio device is rated for USB1.1, which will not support the required data rate in duplex mode.  Terratec achieve it with their Phase 26 USB interface by using simplex mode and their own drivers.

It appears, from a lot of reading, that the best USB solutions involve intermediary converters such as the JKeny modded Hiface, the Audiophileo etc.  any of these will blow your budget severely.

The Beresford for example is 24/96 capable but not via USB - (having just compared that to the coax using 16/44 material I could not recommend it for USB use).

I tend to agree with fmg that the best option could be to use a capable soundcard offering S/PDIF out, Asus Xonar, M-Audio or a secondhand Terratec DMX 6 fire, should all come in relatively cheaply.

If you could find one, the ESI Juli@ could also be a very good option as a soundcard (that is what is used in the Auraliti music server).

Noting what you say, I rechecked and found the following site you may find helpful http://thewelltemperedcomputer.com/HW/USB_DAC_Async.htm and they do say that 24/96 is possible over USB1.1

I therefore tried using the windows direct sound driver in Foobar, or at least to playback 24/96 files with the direct sound USB device selected as output, I was successful in that recognisable music was forthcoming from the DAC.

What is not apparently possible, is to do so using ASIO4all, which only seems to support 32 - 48 KHz sampling rates.  Since I always use ASIO drivers, (one of the advantages of semi-pro soundcards is that they nearly always come with ASIO drivers) I have suspicions as to what the direct sound driver may have been doing to the data between Foobar and the DAC (which has no indicator for the incoming sample rate).

Checking the TI datasheet for the receiver chip used shows it to have a max sample rate of 48KHz and to be limited to 16 bits, that would suggest that even if the DS driver did transmit the full 24/96 that it would not have passed from the USB receiver to the DAC proper.  Further reading of the datasheet for that particular chip reveals that regardless of the rate fed, the output is limited to 16/48.    These details are pertinent to the PCM2902B used in the Caiman as a USB receiver and will not necessarily be applicable to DACs using different USB receivers.

Bottom line of all this is that USB 2.0 audio on Windows does require custom drivers, but that that is only necessary for higher rates than 24/96. 

Have to say the Bladelius does look rather interesting, particularly in a minimalist, lack of clutter way, pity they are so coy about where to get one.

It would be a shame to hobble the UL with a so-so source, it does deserve the best you can give it.