Originally Posted by cpk123
What is wrong with y-connectors?
If only one DVD player is powered up at a time, you may
get away with using Y-cables, even though that is not a recommended practice. It assumes the component outputs of the player which is off go to high impedance when powered down, i.e. a direct output from an active component like an op-amp or video driver chip. That way only the powered unit presents a 75 ohm source impedance to the 75 ohm load (i.e. the monitor, via any switching). The hanging untermimated cables in theory could cause a slight refelection or return loss issue, but for short runs it should not cause any visible defects.
A quick test will tell the story. Connect player A through one side of the Y adapters, then add the unconnected B unit cables and check if you see any visible difference. The connect the B player to the second set of cables (powered off, of course!) and if you are lucky you will still see no change. If you are a belt-and-suspenders type, try the converse starting with only the B player connected, then add the A player powered down. If the unused player doesn't impair the PQ of the one in use, you are good to go.
BTW if both units are unintentionally on, both outputs are around 75 ohms, so the single combined feed is "double terminated", dropping level by half at best, or worse causing a lot of interference between competing video signals. Even "black" or bluescreen from the unused unit is "interfering" video.
Sorry for the long response, but I think you need to know why using Y-cables is not recommended. It might work, but it's not as correct as using a switch that completely isolates the unused unit from the feed lines.
Edit: re-reading OP, I see the issue is 5.1 audio, not video. (oops!) The same issues apply but audio is not subject to return loss, and inputs are usually high impedance, so it is much easier to get away with Y-cables than for video. The unused unit should still be powered down or it may load down the one in use, lowering audio levels.
Sorry for any confusion...