mixing tubes and transistors

the only electric hazzard you are creating is the possible transmission thumps/pops while the preamp is settling down. some of these could damage amps (unlikely but possible) or the speakers (quite possible). if your preamp has a mute switch that should take care of the problem - you would just activate it before shut down. as a practical matter, how long does it take your amp to warm up - most tube stuff takes from 20 minutes to an hour before you have optimal sound quality. unless you have an unusual amp, you could shut them both down and not lose much.

.......no problem with turning off just your tube pre and leaving the SS gear powered up. In fact, if you had a source playing, an "off" pre-amp would prevent a signal from reaching the amp and speakers. I have a similar setup, but can leave my tube pre-amp in standby-- in fact I leave everything in standby except SS amp, and only turn that off 'cuz it hums sometimes. Cheers. Craig

Maybe or maybe not a hazard; damage potential may indeed exist. It depends upon what the preamp does at its outputs when power is applied &/or removed. Some are safe & some are not; if it outputs any transient voltages then that would be coupled to the power amp & then amplified, possibly causing a blown amp fuse or even speaker damage. The safest way to find out is to use an oscilloscope to monitor the preamp's outputs, then turn power on & off while looking for DC component or significant (>100mV) transient activity. If you don't have access to a scope then a VOM might work, or else ask a dealer's service dept. to check this for you; it doesn't take very long & so shouldn't be very costly. Another way to test would be to wire up a cheap pair of speakers & live dangerously. Use some old 4X5 oval speakers etc, from junk.