I have the EP15A. I'm very happy with it. I had a P300 which I sold in favor of the EP. Its quiet but not dead quiet. There are times, not always, when there is some transformer noise. My guess is the power going to it is particularly bad and its transformer is reacting to that. Perhaps a filtered power cord to reduce the noise going to the EP would help. Its well made, good fit and finish. Our power is particularly dirty and a line conditioner is of particular help. The P300 was a big help to me as is the EP. I can't tell you one makes the system sound better than the other. Both of them made a big improvement. EP doesn't claim its output is quite as clean as PS does for the P300 but I'm not convinced the last little bit of power conditoining makes an audible difference. I certainly didn't hear a decrease in sound quality when I went from P300 (100% pure) to EP (99% pure). I wouldn't mind trying their balanced power option but its not worth $900 to me. The EP runs cool, the P300 runs hot. The EP's a conventional shape which fits better on my shelf, the P300 isn't. I didn't think Multi-wave or being able to adjust output voltage between 115 and 120 were worthwhile feautres. The P300 did its best job simply plugging it in and it worked well. I like the EP better for the reasons stated and it has greater amp/watt capacity. I've experimented plugging one of the Pass X350's through it with great results. But it would be nice to start seeing some used ones showing up at lower prices.