: does anyone know anything about tweaking these-i’m considering buying a used one and am wondering about replacing tubes/and also if it’s even worth buying…. To the best of my knowledge the Marshall Valvestate amps have a solidstate power amp and 1 (possibly 2??) 12Ax7 tube in the preamp for realistic tube distortion. I hear good and bad, all secondhand, without ever having played one myself. I’m very curious myself and I’m looking at a 30 watter to play through for a while to test them. On the tubes issue, check out the Marshall website, http://www.marshallamps.com, I believe. Check out the owner/user manuals of your model to wee exactly what it has in the way of tubes. All the best, Silky