Want all the gain you can get from your Classic 20? This is our High Gain Option Retube Kit and it contains a matched pair of JJ EL84's for power along with a handpicked High Gain ECC83S for V1 and a graded high current ECC83S for V2. Just let us know in the comments section if you're looking for max headroom, moderate or an early breakup so we can select a proper grade for the power tubes.