I've got a 568 connected to a Bryston 9B-THX power amp driving B&W Nautilus 805's, SCM's and an HTM 2 and I can definitely hear the difference with upsampling enabled.

I also preferred the CD sound I got when I set my 568 CD input to 16-bit resolution - I'm pretty sure that changes the dither pattern it uses when processing the signal. If you put your ear close to a tweeter when playing quiet passages you can hear different background high frequency noise when you change between 16 and 24 bit input resolution.

I guess it's just one of those things you have to try for yourself but I'll be buying the 568 DSP upgrade to get upsampling on the rears and with DD.

Ronnie

G68XXV, HD621, Bryston 9B-SST, B&W N805+HTM2+SCM1, M&K VX-100 ...