[Agrippa]

Didn't quite know where to put this, but I thought the Lab might be the right place.

Basically I wonder if somebody can enlighten me as to the effects (if any) of connecting the preamp out to two power amps with a pair of y-splitters?  I'd like to be able to audition a new pre without rigging down the one currently connected and since my two power amps both have dual inputs a couple of ys seem like the perfect solution.  In practical terms anyway.  How about it; is this a viable solution?

The pre in question (at the moment) is an old tube amp, which may well have a fairly low output.  However, one power amp has an input impedance of 100kohms and the other has got adjustable gain, so level matching between the two shouldn't be a problem.

Agrippa

[JoshK]

Somebody correct me if I wrong here but simple Ohm's law suggests using a Y-splitter with two amps of equal input impedance will half the input impedance "seen" by the preamp.  In the case of unequal input impedance, the seen impedance is the average of the two.  100K is quite benign, but you didn't state the input impedance of the other.  If it is a tube amp it is probably relatively high.  

I think the issue, more than the impedance that will be difficult is matching the input sensitivities of different amps but you mentioned you have a gain control.  Hopefully they are close enough in neighborhood that that should work.

[Agrippa]

Cheers Josh!  I didn't mention the impedance of the second power amp because I simply don't know.  It's a Denon POA-2400 I just picked up second hand and which is still in the mail.  It's primarily meant to be a backup for my Classe Fifteen, but I thought I'd try out bi-amping and see if anything's to be gained there.  I have no specs at all for the Denon (well, it's 2x200W with a sliding Class A bias, but that's about it), but I'm hoping the adjustable gain will enable me to use it even with an old tube pre.

Agrippa