Exactpower Ep15a or PS-Audio p500

Cytocyle -- point taken. The result however is the same as a unit that regenerates ALL the AC it provides, but with much less power loss (and heat). So I guess technically, it should be called a "power correction" device. For me, the charm is that it doesn't throw the baby out with the bathwater, which allows it to provide high capacity and high efficiency at the same time.

The other thing I like about the Exactpower concept is the fact that it "fixes" those parts of the power cycle it identifies as carrying noise and other artifacts, without the use of the sonics-robbing methods employed in conventional power "conditioners." I just think the use of an efficient Class D switching amp with a feedforward comparison circuit a brilliant solution. So far, I can't find any negatives.
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I own an EP-15A and like what it does.

The rap on the older PS Audio regenerators was that they necessarily were somewhat inefficient due to their use of a traditional linear amplifier to regenerate the entire powerline. Though I don't know the details, and haven't myself heard either the old or new PS units, it would appear that they've changed over to switching amplification now instead.

This would make them more similar to the EP, but without the feedfoward comparator technique, i.e., they still regenerate the entire powerline. Since the switching-amp architecture allows this to be done efficiently, it seems there'd be less relative advantage in EP's method other than greater compatibility with power amps and TVs, while on the other hand the PS approach allows additional features like MultiWave (of which I don't personally know the benefits) and balanced output (which I do, courtesy of my API Power Wedge Ultra's balanced isolation tranformers for sources only, and wouldn't want to give up). I guess one other potential advantage of the EP technique remains that if momentary demand exceeds capacity, the unit simply switches over uninterrupted to unregulated wall power and then back again after demand subsides. However, in my time with the EP using fairly high-powered amps driving 3-way towers in a mid-sized room, this function has never been necessitated at any volume level I can comfortably play.

But I will say this for the EP: Defying some 'conventional wisdom', my present power amp (a McCormack DNA-500) sounds distinctly less impressive plugged straight into the wall than into the EP. So -- maybe an EP for the plasma and power amps, plus a PS (old or new) for the sources?

Zaikes, I echo everything you said (and vice versa ;--) including power amp sounding even better through the EP.

I also wanted to mention a good reason to have the regenrator and balanced power unit as separates: The regenerator can/should go near the amp(s), powered speakers(Logans in my case) and powered sub(s). A BP device is useful near the source equipment, which may (probably) not be near the speaker/amp end of things, and will probably not need to be the same (high) capacity as the regenerator device. In fact I run a 15 foot 10AWG umbilical from my EP-15A over to the balanced SP-15A near my front end stuff. The whole system is "as quiet as a chair!"
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I have not used exact power products but I did have a PS Aduio 500 unit for several months in my system. For me at low volume and soft piano playing the unit was audible and for that reason I switched out. I am now using a SOund Applications X-12, which is very much to my liking. Not sure how loud or what you listen to but soft piano heard at low volume can be covered by the fan of the PS 500.

Well, scratch my speculation about the new Power Plant Premier using a switching output amp. When I ACTUALLY WENT TO THE PS AUDIO WEBSITE AND READ ABOUT IT (real tough, that!), it was made clear that what's different now is a new type of tracking power supply, but it's still a linear amp, said to be pretty much the same as before otherwise but with a claimed 85% efficiency instead of 50% (Exact Power claims 97% efficiency for the EP15A). PS maintains that class-D topology isn't compatible with a power regenerator (they do use ICE in power amps) because of ultrasonic noise.

The Power Plant Premier (they dub it P3) now also features the ability to switch over to unregulated wall power if capacity is briefly exceeded (such as when an attached power amp is turned on from cold), like the Exact Power. Strangely if you ask me, PS doesn't play up their product's ability to deliver balanced AC without having to resort to an outboard balanced isolation transformer-based device. But it does now feature five of what they call "Iso-Zones" -- what appears to be a combination of inductive and parallel filtering applied to each of the five outlet duplexes, said to provide inter-component isolation -- similar to (but presumably not quite as absolute an isolation as) what I presently get from the API Power Wedge Ultra iso-tranny unit following my EP (who also offer balanced iso-tranny units to follow the EP15A). But I'd need to add yet another transformer-based component to get balanced AC to my power amp. Seems PS have also added a remote control, turn-on sequencing, cable and tele connectivity, and reduced the Multi-Wave complement down to one choice, the most popular one. And incorporated the surge protection into a removable module that can be more easily replaced in the event of protective failure.