It's no secret that Stevie played his amps cranked and preferred a little cleaner sound from the front end allowing you to hear more power tube breakup. This kit uses a JJ 5751 for V1 which is in-between an ECC81 and an ECC83S in gain along with four ECC83S's with one being current balanced for the phase inverter and a GZ34 rectifier tube. The default power tubes are a matched pair of the JJ EL84's. With the Customize option you can configure this kit to use the JJ EL844's which will drop the power output a couple decibels (ideal for players wanting decreased headroom/output).