Amp and preamp on same outlet?

Unless you have issues with too much current draw, just plug 'em in together enjoy and don't worry about it.

If it were a problem for me with my gear, I'd probably just buy different gear that works better together and be done.

If you have noise issues doing it the simple way, then you have a problem somewhere else and better to address that appropriately.

Or if you have a second outlet on a different circuit try that as an option. If it sounds better to you then keep it there otherwise it doesn't really matter.

Jea,

I will agree that sound quality usually benefits from proper power conditioning. There are many ways to achieve that effectively. Best approach will vary case by case. A dedicated circuit can introduce its own problems associated with grounding as pointed out so it is not a panacea in of itself. Alone, even if doe right, it might not make any difference in any particular case just is it may in others.

I'd think about applying a power conditioner and perhaps noise limiting power cords to line level devices first in most cases. Of course one can take things as far as they want if they deem it worth it.

Move to a more efficient amp like Class D and no problem ever. I have both my 500w/ch monoblocks on the same outlet and dynamics match teh best I hear anywhere and are teh best I have ever had myself.

Efficiency done well is always a good thing.

My circuit breaker used to go frequently with modestly high power power sucking Class a/b amps.

Now the only time it might go is if I power up both 500w/ch Class D monoblocks at the same time. They never show any signs of strain or break a sweat running. Plus I can leave them on most of the time and teh impact to my power bill is negligible as quality power amps tend to go, so overall cost of ownership is lower as well.