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Old 21st May 2006, 02:02 AM   #1
mourip is offline mourip  United States
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Default Building a Preamp:Dual Outputs Question


This is a general question that I could probably ask in another forum but since this forum is so easy going and helpful compared to others I thought that I would ask here.

My only source is a USB NOS unbuffered DAC with a pair of Sowter transformer volume controls built in. Right now I have one pair of RCA's wired in the rear but I have two amps that I switch out for different purposes but only use one at a time.

My question is: if I add another pair of jacks to the back so that I do not need to switch cables back and forth can I just wire the two pairs in parallel or do I really need to switch them? I am concerned about the effect on the sound of adding a switch but perhaps that will not be as bad as having my passive pre driving two amps at once even if I only have output coming from one at a time.

Any takers?

Thanks a lot!

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Old 21st May 2006, 02:23 PM   #2
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IMO, you should install a switch. Your concern about loading effects is WELL placed. Don't cheap out. Buy something of high quality with Silver contacts and sealed construction. That way, any undesireable sonic impact will be held to an absolute minimum.
Eli D.
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Old 21st May 2006, 04:19 PM   #3
kevinkr is offline kevinkr  United States
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I'm with Eli on this one. Worse unpowered amplifiers depending on topology can present a highly non-linear load to the device driving it. Also of course is the effect of the internal input impedance (resistance and capacitance) and cable capacitance of having two devices connected in parallel. Not too much of an issue with active pre-amplifiers with sufficiently low output impedance, but a big issue with any passive..
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
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Old 21st May 2006, 07:19 PM   #4
mourip is offline mourip  United States
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Thanks Eli and Kevin,

I guess that I knew the answer. You were correct about "cheaping out"

I appreciate the straight answers. Thats why I asked here.

I guess it's time to get together a Michael Percy order...


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