Two systems in the same room

You will get some interactions between the speakers in use and the ones not in use (sympathetic vibration). it is also difficult in terms of room acoustics.

Here is a thought. First I assume you can afford speakers which will accomodate both types equally well.

Just set up a second set of electronics for the same speakers - one tube based for vocals, soul, and jazz, the other SS based for rock, etc. Have two runs of cables to the speakers with banana plugs so you can connect either system in about 5 seconds.

Works for me (I actually have three different set ups and one set of speakers.)

We've had to do this for some of our dealers. There are definitely tricks to help, one is a tapestry that can be hung out in front of the system not in use, but there are other things in terms of directing sound energy that can reduce the interaction between the two.