I'm pretty sure you won't hear any difference.
Dunno about your Cable TV, but many recent DVD players employ 24/192 upsampling anyway, so there won't be any effect.
That said, I'm not a big fan of upsampling:
only the very best CD players succeed in avoiding sharp treble edges and shifty staging.
I have a cheap 16 bits 44 kHz DAC that sounds just fine.
But I didn't hear any ill effects when setting upsampling to ON in my 990, so the chip must be a benign variety...