I have not heard the PX 25, but my buddy speaks highly of it. His ranking is Lampi anniv mesh 45 globe, Px25 and then Kr242/ EML solid plate 45 globe. He has the Px4 but hadn't used them in so long, he forgot. He is not a 300b lover, but was pleased with the Elrogs till they died.I have a WE 422A for rectifier, and primarily use Takatsuki 300B for output. I'm tempted to try PX4.