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Two sources, one sub - can I use Y-cable

I have a Musical Fidelity A5 integrated and use the PreOut to connect to my subwoofer. When used in the "Home Theater Bypass" mode the PreOut is inactive (no signal). If I hook the single end of a Y-adaptor into the sub input and hook 1 of the 2 other ends to the MF A5 PreOut and the other to my Rotel 5.1 receiver's sub out am I asking for trouble? (this would provide one signal or the other to the sub). Would the Sub out from the active amp end up "driving" the output of the inactive amp? [I do have a switch box that could used to manually switch between inputs but that does require human intervention!]
hlesser
shadorne's avatar
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shadorne
7,467 posts
 
No. The output impedance of the pre-out may quite low and will drop the active signal level going to the sub.

Y's in audio are a nightmare. You can only use them to split signals from one source to two high impedance inputs.

If you want to connect outputs together then you need a resistor network box to maintain impedance levels remain high enough so that no source gets damaged/distorted.

See this Passive Mixer

or, if you want to do it properly then you really need a high quality active analog mixer (these are used in studios everywhere for patching gear).
elevick
2,636 posts
 
I agree with Shadorne. Don't do it. You can buy a simple switch box if need be.
reubent
6,952 posts
 
I use an NHT SubOne(i) which has both LFE and two channel inputs that can be connected at the same time. It is a discontinued model now, but I'm guessing the current NHT subs offer the same feature.
stringmun1
21 posts
 
I have multiple source material (ie HT and my main 2-ch listening system. I use aSescom stereo selector box to manage hte I/O. Works great!
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