I updated my ref 5.2 to 5.32. In fact, this upgrade means the replacement of USB interface based on Tenor 8802 chip for the new card 'usb32'.
I've always used this Dac through its usb and it has been amazing. But this upgrade, this new interface usb 32, exceeds expectations. There is an obvious increase of the dynamics and textures. At this low price (i think USD27,00, plus shipping), this upgrade is very worthwhile.
So i think the Ref5.32, in use through its usb 32, is a very good option in hi-end audio. My system is not a headphone set. It is based in Electrocompaniet amp and Kef Reference, and this type of equipment is very demanding with the sources, and this Ref 5.32, specially with its usb32, is very good indeed.
*I'm running this DAC through its usb 32 under MacOs Mountain Lion. Later i'll try to test this system under Win7.