@duketbrd88
to answer your earlier question
xlr is theoretically the better connection, but for high end home audio 95+% of the time single ended (rca) connections work just fine with zero sonic penalty in a properly set up system ... especially using short (less than 3 meter) interconnect runs
then there is the matter of dac designers and how/what they optimize in their output stages.... two prominent, well respected designers of dacs... mojo audio (ben zwickel) and msb (jonathan gullman), both clearly state that they feel their dacs sound better, more natural, more harmonious, through their single ended outputs... even though they offer xlr’s for the convenience of their customers (ben charges extra for xlr as it involves more circuitry)
regarding lack of perceived bass at low volumes, you should search ’fletcher munson effect’, there was a recent thread here discussing that
always, always, compare two sources at the SAME volume when trying to hear sonic differences... your cell phone has easily downloadable ’db-meter’ apps, go to app store... play test tone, note volume settings to make two sources equal, then adjust before evaluating...
...and if you bought the accuphase dac card from a dealer, i would certainly push them to exchange a fresh one, so you can be sure yours in hand is not problematic