My Denon 2900 has "the latest Burr Brown 24 bit 192 kHz" d/a converters. It does sound great on standard discs but does the presence of the 24/192 converter, in itself, suggest "up-sampling"? If not....what does?
isnt "upsampling" the addition of filler bits?

Either way, the only format out there that will do the 24b/192hz sample rate is DVD audio, and not alot of DVD audios will go higher than a 24b/96hz sample rate. It all depends on what rate the disc is encoded.

it will not, however, to my knowledge, upsample the CD rate to 24b192hz
Check your user manual or look for an indicator on the front of your player that says "upsampling", etc.
The Denon marketing staff wants you to know if your player is doing this on redbook CDs.
My Philips 963 certainly does upsample and it sounds great!
GO CUBS!!!!!!!!!!!!!!!!!