solid state gear- leave on?

Absolutely! They sound best when left on 24/7.

Depends a lot on the design of the amp. With some I would do it, but no way I would leave older klass A monsters on all the time. The power bill would simply be a killer..
Even non klass A amps that dont get that warm can draw a lot of power in iddle mode. So my advice would be to check how much they use - and judge if you think its worth it..

Once i turn mine on i leave it on all day. however; i always shut it down when i go to bed or at night when we are done listening.

Chuck

I would like to "third" the recommendation to leave your solid state gear on all the time. Two of my components are by Simaudio and that is their recommendation for all their products. A Sim dealer once told me that my I-5 integrated would need 300 hours (!) on to reach its best performance and some audiophile friends have reported improving sound well beyond the 100 hour mark.

Best,
Lee

Generally speaking, it's not heat per se that hurts components, but rather the hot/cold cycles that occur when they are turned on and off. Everything expands or contracts in response to heat or cold, and the repeated expansion/contraction that occurs when components are turned on and off wears down components over time.

Thus, not only do components sound better when left on 24/7, they are much less likely to break (it's counterintuitive, but true).