Want all the gain you can get? This is our High Gain Option Retube Kit for the Jet City 5012C Combo and 50H Amps. It uses a standard ECC83S in V4 for the FX loop along with four handpicked High Gain ECC83S's with one being current balanced for the phase inverter in V5. The default power tubes are a matched pair of the JJ 6L6GC's but you can configure this kit to use the JJ KT66's, 5881's or even the JJ 6V6S's to drop the power output a couple decibels by clicking on the "Customize" button!