How many inputs does your tv have? and are you hooking up by component or S-video. If your tv only has 1 set of s-video and no component, get a box from radioshack with more s-video inputs or hook up by rca only. I have a 501, a 6000, a direct tv reciever, and 2 dvd players hooked to my hitachi( it has 2 component, and 3 s-video inputs)
I have to assume you have an HDTV TV since you have the 6000. You would hok up the 6000 via component to get HDTV. The non-HD recvr. could be hooked into the S-video input on the TV or, at the least, via RCA cables.
We have our 6000 hooked into the plasma for HD via compnent. The other sources are via S-video (DirectTV via VCR) and another VCR as well. Since we have two S-video sources i am using an inexpensive RS switchbox to switch between the two to feed into the one input on the plasma.
I have three satellite receivers plugged into one of my TVs (two of them are a 6000u and a 510), so why not? Most RPTVs I've seen have at least three input jack sets. Mine has seven: 4 composite, 2 component and one DVI.