Details for bi-amping

You do not need two preamps. You can use Y connectors from a single set of outputs, that is what I did when I biamped. Use good quality Ys. It is not clear if you are using 2 matched pairs of amps or 4 different ones. In the first case you will need level controls for the pair of amps that is more sensitive, ie plays louder as a given preamp setting, so you can lower their output. Using mismached amps would require 3 level controls at least and be quite complicated to set up.

Thanks Stan for your quick reply. My ignorance needs a lot of clarification. I intend to use two matched pairs of monos. As you said in this case I will need a level control for the more sensitive pair. Saying "sensitive" do you mean more powerful? If yes, how could I make this setup? Obviously the level control of the single Pre-amp is not useful for that because it would attenuate (lower) the output volume of all the four monoblocks.

Parts Express carries the Harrison Labs fixed inline attenuators in 3, 6 and 12 dB versions. Right now, your guess is as good as mine which you might require but you only need them for the amp with higher gain.

My experience would advise to stay away from variable, potentiometer based units.

Passive volume control attenuators, such as Goldpoint, can be too rough for fine tuning biamping configurations and have fixed input impedance. Which brings up the other consideration of parallel amp impedance getting reduced and whether the preamp can handle that. Usually not a problem for solid state preamps.

Fair warning: Many biamping experiments, passive or active, end in failure because it's far more complicated than most people anticipate or are prepared to understand.

I am concerned that unless you have 4 exact amps, and 2 exact stereo preamps, the sound may be difficult to meld inaudibly.
Its not just a matter of gain matching at a particular frequency, but to track all the sound at any frequency exactly right....and too the dynamics have to be the same or the system will sound different at different sound pressures. If you listen to classical music or jazz at all, this would be of great concern.

Wow, what a bunch of nonreading and confused writing.

The OP first writes that he wants to use tubed amps on the top and SS amps on the bottom; later he writes that he wants to use indentical amps. Which is it? Tubed and SS or 4 identical amps? I suspect it's the former.

One preamps will do, and in fact the use of 2 preamps will complicate matters substantially. Y-connectors work just finely and are almost free. After you decide if you want to continue your experimant, you might look for a higher-resolution solution.

Stanwal is correct that you'll need some way to reduce the Voltage gain (NOT 'sensitivity') of the higher-gain amp(s). Of course, the easiest way to do that is to turn down the level of the higher-gain amp. However most poweramps don't have gain controls, so you'll be stuck having to use the passive attenuators that Ngjockey mentioned.

Good luck. I suspect that you'll decide that it's more trouble than it's worth.
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