I, too, (like RCF051) listen to a lot of jazz. But also classical. I found that 5ch or 7 ch stereo is really nice, not to belittle the upsampling mode.
7.1 Direct is used either for SACD or for 4 channel inline, playing back material in four discrete channels (as recorded on 4 channel Crowns years ago). I have played with and compared setting speakers to small so that it is digitally encoded and sends info to sub...and setting to large. Both sound great.
Actually I think this equipment is so teriffic, that it's hard to beat it in any mode!!!!!! And for that system (of the two I have) I haven't yet done the firmware upgrade. (I know...wife says I am the chief procrastinator).
On a positive note: I removed the Alesis EQ. Now sounds better. Happy days are here again.