Plugging directly into the wall is great, but the problem is you're open to spikes, current fluctuations, etc. A line conditioner/power conditioner is no good for an amp because it limits dynamics and restricts air/three dimensionality. I've tried lots of stuff and the best I've found is the PS Audio Ultimate Outlet (high current model). I've found virtually no difference between the UO and plugging into the wall - the UO has the advantage of providing protection to the amp without limiting dynamics, etc. I think it's because the UO doesn't "filter" as most line/power conditioners do. It just cleans up the AC, nothing more. As soon as I plugged my amp into the UO there was a tremendous increase in soundstage, bass, air, and blackness. It sounded just like plugging into the wall. But, just make sure the UO is dedicated SOLELY to your amp. Don't plug anything else into the second socket - if you want to use a UO for your front end, get a separate one.
An interesting side note. If you're already using a line/power conditioner, DON'T plug that into a UO since I've found that doing so is very limiting to sound - guess it's too much overkill.
Enjoy.
