I think like you, not fair comparison. Big difference in sound, for me, between SE and PP. Preference depend on preferred music and environment. I like and enjoy them both but my preference for my music taste leans towards SE. That and the Prima is a much more expensive amp. The little Zen, I assume this is the one being discussed, is what it is. An American built SE tube amplifier built at the cheapest cost using decent parts. For me, not a lot of difference between a PP tube amp and a good SS PP amp.