I understand better now, thanks for the knowledgeable posts above. Class D is analog, but it is solid state. I remember here in the UK the old HH solid state amps - they were marketed in the 1970s as the answer to the maiden's prayer, but didn't succeed because of their harshness. I remember being in a band and the other guitarist was playing a Telecaster through an HH amp and standing near that combination was like being sliced with cheese wire, or that's what I said to hm and he wasn't best pleased... Anyway, I'll steer clear of the solid state BluGuitar and stick to lugging around my Marshalls, much as I'd prefer a more easily portable product.