How do I hook up 2 preamps to one amp

I have a Luxman CL38U SE and a Krell Showcase processor for movies. On my Bryston amp I hook up the RCA outputs to the Luxman and the Balanced outputs to the Krell. I just flip the switch on the amp. I've had tube preamps for years and this saves tube life on the preamp as HT pass through requires having both preamps on.

I have a similar situation with an older Rotel processor and Denon receiver. I was going to try this method but then thought about the sub. I want to listen to 2.1 but also have the sub available to the Denon for movies. Any suggestions?

I agree with Herman after all. Why use the NAD at all? If you need it for phono, just sell it and buy an NAD phono. THey are cheap. Go with the Lex only.

"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.

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.

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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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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.

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.

If the stereo preamp has a Home Theather bypass input, you can connect the Krell front LR pre out to that input.

When you are watching movies, switch the stereo preamp to HT bypass mode.

My Bel Canto Pre3 has an input I can configure for that.

As for my Audio Research Reference 5 (PROC mode).

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Elizabeth,

What he said about the tape loop or what he said about just using the Lexicon?

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Herman has it right. Line out to line in always works and tape outs are independent of front panel controls. But based on the rather funky arrangement and weird signal flow, combined with probable tape output selectors, lots of ways to get confused and have no sound (flipping buttons madly trying to get audio until YES full output into the amp). Simple is always better sound anyway, use everything through the Lexicon....It must have a 2 channel mode......

Brad

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I considered that too but since I have no experience with either decided not to comment.

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Kartez and Herman, tell me if I'm wrong but...aren't most Lexicon units superior to most NAD's? Why not lose the NAD?

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When you use the splitter you are effectively hooking the 2 preamp outputs together which is never a good idea.

I haven't used a tape loop in a while but I don't believe that would work as described. The tape in from the Lexicon would be controlled by the NAD volume control if you use the regular outputs. It is the tape out that isn't affected by the volume control but if you use that then you won't be able to control the volume for music either.

Use the normal pre outputs from the NAD to the input of the amp. Take the Lexicon front L and R output and put into any unused input on the NAD including tape in. Choose that input when watching videos. When you do, set the volume control on the NAD so it matches the level when you have the Lexicon hooked directly to the amp.

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You could run the Lexicon through the tape loop on the NAD. The tape loop is independent of volume control and should pass through a full signal.