1 preamp out to a 2nd preamp in any harm?

I want to run a mono signal through the one preamp to a solid state 300 watt monoblock and then to the sub and from there to all the woofers in my other speakers. With the other preamp I will send the signal through a tube amp to the mids and tweeters. I like the sound of solid state in the bass and tube in the mid/tweeter range. Just don't want to destroy anything in the process.

I like the KISS principal myself but whatever floats your boat. The more things you put in the reproduction chain the farther it will be from the original sound but if that does not bother you go ahead.

I think what you want is very common and one solution is to use Y connectors on a single preamp's main outs with one leg of each going to 2 different amps. That would be less likely to distort your distortion in chaining preamps.

I don't understand several things about this:

1)The woofers in the main speakers will presumably be handling much higher frequencies than a sub would normally handle. Assuming that the overall setup is intended to provide stereo (is it?), I don't see how it would make sense to provide a mono signal to those woofers. Driving a sub with a mono signal can be appropriate only because the frequencies it is reproducing are very low.

2)How are you generating the mono signal?

3)Assuming the sub is a powered sub (is it?), containing its own amplifier and providing a level adjustment, I think you are saying that the reason for including the second preamp is to allow level-matching between the woofers in the main speakers and the mid/hi drivers of the main speakers. Am I understanding that correctly?

4)Can you indicate the make and model number of the sub, which may help to clarify some other things I am uncertain about?

Regards,
-- Al