I remember reading a great review of the P300. There were however two things that you might want to consider. The review stated that your electric bill will take a big hit and also that it is meant for amps up to 200wpc. He stated that they will have new bigger models, but that he felt they would be too expensive to run. I don' have the specifics, so I am only repeating what I remember. Maybe you should track down the review. It was recent in either Stereophile or TAS.
