Amp ac cable connection

If you are in an apartment building or condo you may benefit from conditioner as there will very likely be a lot of noise in your AC, and conditioner may improve sound even as it limits current. If you are in a single family home near a transfer station with your amp on a separate line and breaker in your home, your power is likely less corrupted and going straight to the wall should sound better.  As suggested previously, just try it both ways if you can get a conditioner on loan from The Cable Company or other source.

Mitigating decision is whether or not you are in an area prone to electrical storms and at risk of frying your investment with no protection. I lost a TV that way.

Benjie, everybody comes to this discussion with different power service, gear and ears.  While there may be an absolute sound many are seeking, there are many paths to get there. Power conditioning is one of them and has it's uses and benefits. I choose not to use it on my amp in my home system with a dedicated line and breaker, but it is a must in my office to get the most out of my system there, and for family members who live in large apartment buildings (in my opinion).  As with all things in this hobby, YMMV and careful listening is the proof in each instance.

Not everyone agrees that power line noise is not problematic and therefore not in need of attention, including equipment designers, with some form of line conditioning built into at least some high end amplifiers (one example: http://www.stereophile.com/solidpoweramps/407ayre/index.html#C4GXsiFsx3lHdP7s.97). Perhaps why at least some high end systems are better able to navigate potentially dirty hotel power relatively unscathed in demonstrations, dunno. I will say that I have seen power line conditioning included as part of some very good sounding demo systems - maybe that was the Shunyata room;-)

But the fact remains that some audiophiles actually prefer the sound of their gear in their home fed from power conditioners... even their amps. Listening and preference are profoundly subjective. That is why there is a market for different audio solutions, with different tube and solid state amplifiers highlighting different aspects of performance, some on the soft and warm side and others on the crisp and fast side. And as described above, different conditioning products have different approaches and produce different results.

I agree with many here that power conditioners change the sound of their gear, and perhaps especially their amplifier. I also agree that that change is not always for the better. I disagree that power line noise is not a potential problem in some instances. The most important point is how does your system sound to you, and what sounds more like a real performance in your listening environment. While experience and advice given here are all valuable data points, the definitive answer can only be determined in the end by the individual listener in their listening environment. A very long winded way of saying try your amp with and without conditioning.

Some basic information on power line and common mode current noise for interest.

http://www.arrl.org/power-line-noise

http://www.eetimes.com/document.asp?doc_id=1274125

http://m.ecmweb.com/content/troubleshooting-electrical-noise-0

and for fun, if you want to try to detect noise yourself:

http://www.w8ji.com/power_line_noise.htm