Who has Caps on their AC lines ???

Gordus above is right. The 120V power lines actually have a peak to peak value of 340V. 600V rating would suffice. Fuses also a good idea.

I should have clarified that the 250 volt rating that i previously mentioned was for the working AC voltage, which is different from the DC working voltage quoted for most capacitors. I agree that a higher voltage rating is better, as the 120 volt ( nominal ) rating of U.S. based AC systems is an RMS rating, not a peak rating. AC peaks will typically run at somewhere around 160 volts during normal use. Having said that, the peaks can be measurably higher than this, especially if one is talking about heavily distorted AC or spontaneous spikes and surges. As such, it is better to be safe than sorry.

As a general rule, a cap rated at 400 volts DC will typically spec at appr 250 volts AC. Going to a cap that is rated for 600 volts DC offers even more headroom, but at increased cost. For as much money as we spend on some of these other ludicrous and far less beneficial "tweaks", splurging for higher rated caps can buy a lot of peace of mind for not that much more money.

Musicfile: I've used Xentek and Topaz "ultra-isolation" units in the past. These are superior to their standard "isolation" transformers, as they typically offer appr 20 more dB's of common mode noise rejection. Having said that, even their standard models are typically far superior to a toroidal design, as they typically offer appr 30 - 40 dB's more common mode rejection. Just make sure that you choose a unit that is rated for well above the intended draw and that it has a "gonzo" sized core. The actual core size may be more important than the actual rating, so long as one is not trying to run the transformer at or very near rated capacity. Sean
>

I guess the first time I tried this was the Van Evers. Since then I have tried at least two others. In my system all it does is to hurt the sound. Removing them gave me a big improvement.