Assume zone 1 is main zone...Denons have a feature on some of their avrs to have different audio/video (on mine with the remote use setup menu to inputs/video source/video select) altho I've never used this feature with my Denon (4520) and I assume this is for use within the same zone...altho if I go to the network input settings (assume BT plays thru network?) then I get no choice of video. I think the source has to be video based itself; for my blu-ray input I have video select choices of: default, cbl/sat, dvd, blu-ray (which I find curious as assume that is default but didn't dig into the manual for an explanation),aux 1, media player only. I've never used this feature, just noticed it before. I've never tried to use this feature, tho. What does the 3500 manual indicate?