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.

Many tube pre-amps have no problem being left on all the time. In fact many recommend it. Tubes in many will last years depending on how much voltage the manufacturer runs them at. Some also have a standby mode. We never turn any of our tube pre's off. This is not the case with all of them and you should check with the selling dealer as to his experience.

A number of preamp tubes do well if left on (last and can perform well depending on time constants in design & warm up time). Without knowing yours I can't comment further, but your dealer and manufacturer can give some advice.

Even with mute activated, I have found (through a well-meaning visitor who decided to "help" me) that some preamps do give a pretty significant pop when turned off. As others have commented, I would worry about damage to the speakers. Bob_bundus' suggestion seems excellent to me...

Good luck,
Jacob