How do I hook up 2 preamps to one amp


I have a NAD preamp that I use for music. I have a Lexicon preamp that I use for Video. The problem is I have 1 five chanel amp that I need to use for both preamps. When I try to use rca splitters/y adapters, my speakers play at a low volume. If I disconnect one preamp, the speakers play louder. What should I do to allow both preamps access to my 5 channel amp and not have humming or low volume.
kartez
Go to radio shack and buy a double pole double throw switch. Connect each pre to one side of the switch and the amp to the center. By flipping the switch you will alternate between pre A or pre B feeding amp C.
what Elevick said is the answer - both of his posts. I'm not sure what Lexicon you're using but it's likely to be superior to your NAD - even for music, but if you prefer the NAD, then what you do is connect the the speaker outputs (ie Main L/R) from the Lex, to one of the inputs of your NAD. This can be Tape in, or any other unused input. When you watch video you pick set the volume level of the NAD to a level that is easy to remember and repeat - for example - 12:00 position. You calibrate your HT volume levels at this setting, and any time you watch HT, you return the NAD volume to this level. This way the volume control of your Lex will control your HT volumes - and pass through the NAD.

This all assumes your NAD doesn't have HT Passthru. This is the safest, lowest cost, and best sounding of all options for you.
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what Elevick said is the answer - both of his posts.

BDG,

no, he said to run the Lexicon through tape loop which will not work. In fact, I don't really know what that means. How do you "run something through the tape loop"?

What you said will work which is basically what I said.

Perhaps he wants to use the NAD for music because it has a phono section. In that case he could feed the tape out of the NAD to a Lexicon input, the Lexicon preouts to the amp, and use the lexicon to control the volume for everything.

Otherwise I agree just ditch the NAD.

I don't like the idea of a switch either. You need another set of cables and have to build a box to house the switch and connectors unless you want to cut the connectors off the ends of the cables.. It is unnecessarily complicated when there are much easier ways.

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thanks Herman - yes, I re-read his after I posted mine and realized I misunderstood. I agree with you - it won't get to the power amp that way.

The way I described works very well - I used it with a Musical Fidelity Nuvista preamp and a Lexicon pre-pro. It's not as clean as if you have a true HT bypass in your pre - but with a quality preamp you will not notice any difference.
"This is the way I did it" All my parts came from Radio Shack. You can use expensive "audiophile" parts if you desire. First I constructed a small wooden box to house the parts. After I sanded, stained, and shellacked the box; it was quite attractive.

Next I drilled holes for the small red rectangle rocker switch and six female jacks. After installing this, I soldered wires from the jacks to the switch; L & R in from each pre, and L & R out to the amp.

I now use that same box with the 6 female jacks and rectangle rocker switch on another project.