Try the Running Springs. I use one for my power amp and another for sources (preamp, DAC, CD transport etc). In some systems, they need break-in. They are excellent - one of the greatest "bang for the buck" deals in audio.
Theo, you might want to take a look at a review I posted here on the GON that concerned the Running Spring's Jaco. I had tried at least three other companies gear and found the Jaco to be superlative, with no downside at all.
The guys who own and run Running Springs are great gentleman and were fun to deal with. I also agree with Kmccarty that their products are very reasonable priced for the level of both build quality and performance compared to other companies.
This is the only conditioner has made a positive impact in my system. I bought 2 pcs Duke for my power amps and after working with them for a month I removed and replugged the amps into the wall again. The Dukes did nothing for the amps, so I plugged my pre and cdp and the Duke really generated low level details into focus and clarity. In other words the tiny sounds that is barely heard is now louder and easy to hear. It appears that the Duke has quieted things down a couple of notches. The snaps are much sharper and closer to real life.
The Duke will be staying for many years to come.
That is correct, there where no change in sound out of the power amps with the Dukes plugged in or not. My resident power cords are ESP Referance, PAD Dominus Ferrox and Venustas.
I listen at various times during the days and nites, evert day of the week with the same results. I think my Pass 350.5s does not mate very well with the Duke. And because of this I plugged my pre and cdp into the Dukes with fantastic low level detail improvements.
That's an interesting observation regarding the power amps. I've actually had the opposite result. There was an immediate and very noticable all-around improvement when I bought a Duke for my JC-1s - and I live in an area where power is relatively clean to begin with. I wouldn't voluntarily do without it now.