Power conditioning

"Generally" speaking; power conditioning works well with preamps and source components. Most (not all) amplifiers do better plugged into the wall. Especially the larger ones. The only way you'll know for sure, is to try it yourself. If your power is really dirty, the a conditioner might be the way to go. Only you'll know that.

Most manufacturer's "recommendations" like Brystons are done for legal liability purposes. So if you blow up the gear playing around with the power it is your fault..

VH Audio recommends installing two .47uf/600v Auricap between the hot and neutral on your wall outlet for a cost effective power cleaner that does degrade current flow.
I haven't tried yet, but have the caps on order.

A new company on the power conditioner scene is puritypower.com. Looks like this monster can handle
anything.

Another inexpensive alternative would be to try a OneAC transformer available on EBay. Make sure you allow about 50% head room on amperage and don't pay more than $10.00 per amp! These are nice units and very upgradable with Kana813's recommendation.

Received a 12 amp Powervar yesterday and tried it with my Marsh A400s plugged into it. Didn't expect much but am leaving it there. Got it for other duties but detail and openness along with a better S/N ratio means it's staying for amp duties. I listen to music loud at times and cranked it for quite awhile last night. I could not detect any signs of compression or any other anomoly, just the cleanest sound I've ever had. Listened particularly to the bass which is where I thought it may show signs of weakness. The speakers I'm using have four 15's and two 10's for bass. The clarity of the upper mids through the treble is quite pronounced. After reading Bryston's and Naim's articles on not using a power conditioner with your power amp I'd not really considered it, especially with all of the user comments regarding compression etc. I'm very pleased they are wrong, at least in this case. I've got a dedicated 20 amp line but live near a commercial area and not far from an industrial area so my power is no doubt pretty dirty. Just didn't expect anything from adding this power conditioner especially since the Marsh has filters for the power coming in not to mention a huge transformer and four large Nichicons in there. The improvement was obvious almost instantly and still is a day later. Have several hours of listening in at this point.

I heard a system with P2000 preamp and A400S with and without a line conditioner. The line conditioner smothered the life out of the music. Metric tons of detail loss. Sound stage collapsed big time. So I think line conditioners, acting potentially as an agent of increase in power source impedance, should be avoided. Once I clamped on those ferrite filter devices onto the power cords of my entire system. Guess what? It did pretty much what the line conditioner did. So I'd reexamine your conclusion that the conditioner is improving the sound. Some interconnects will fool you upon first listening into thinking they've made an improvement. But with continued listening, you find that what they've done is filter out some detail, which brings other detail to your attention. Just make sure you aren't falling for this gotcha.