Mono Block tube amp or Stereo Tube amplifier?

Start with why you want tubes. Then think about how much you can spend. Personally I believe that tubes are for acoustic music. I see no reason why anyone would benefit from reproducing heavy metal at 95 db with tubes. That is SS territory. Tubes are for sensual, subtle sounds.

If you still think you want tubes, or if you now see bi-amping with SS works better for you, the rules are the same. Two chassis cost more than one. Monos enable you to shorten speaker runs. Monos, even if they share a chassis will have separate power supplies allowing for better separated channels. Then there are layout implications, bragging rights and forum topics.

Remember, though, that bi-amping is not a goal but a means to reaching one's goal. Unless you need to do it, don't bother.

Bojack -

I don't know if RUSH uses tubes and I certainly don't know why they use tubes. But if I had to guess I would say it is because of the way they can make them distort.

The point I tried to convey is that tubes are better able to provide the delicate nuance available to the discerning listener of acoustic music. Amplified, cacaphonic noises can be conveyed by any kind of amplification, it is true, but why waste tubes on it?

Similarly, one cannot audition any kind of equipment with electrically amplified music because there is no live standard to compare it to. It always passes through electronics and it always comes through speakers. The best you can do is compare speakers to each other.