Supro S6420+ Thunderbolt Plus 1x15 Guitar AmpThe Supro Thunderbolt Plus is a single 15" combo amp which is switchable from the original 1964 design of 35 watts Class A to 45 and 60 watt modes which are Class A B. Normal and Extra hot input options, combined with a wide range of available gain on tap, allow you to fine tune the texture and response of this amps massive sound. Turned all the way up, the Thunderbolt exhibits nearly zero self noise, yet it puts out enough volume to be easily heard