Audio support / interface
So the Audio is setup to use ASIO to interface to the DAC.
This means that the music data is sent directly to the DAC without any intervention from Windows or even the Xonar audio console - it literally gets delivered at the DAC's doorstep.
This means that if you made a bit-perfect rip from a CD, you will get a bit-perfect delivery to the DAC. It also means that no jitter is introduced by the transport itself.
It also means that you don't have to do anything to switch between different sample rates or bit depths - it's transparent and hassle free.
One implication is that the windows volume control doesn't work (remember it bypasses Windows completely).
The options for attenuation are as follows:
1) Have the maximum signal go to a pre-amp and attenuate from there in the analogue domain.
2) JRiver has an option for changing the 'internal volume'. This effectively attenuates in the digital domain before the data is sent to the DAC. Now because JRiver user 64-bit data structures for processing the music data this kind of internal attenuation effectively has no negative effect on the audio.
Therefore this option allows for plugging the TFS directly into a power amp and bypassing the pre altogether.
3) As above but use a pre to set the ball-park volume in the analogue domain and tweak it from the comfort of your armchair in the digital domain with the 'internal' volume control.