So you gotta have more gain from your Mark V Simulclass amp?? OK, this kits for you! This is our High Gain Option Retube Kit and it contains a JJ 5U4GB rectifier tube, three handpicked High Gain ECC83S's for V1 thru V3, three standard ECC83S's for V4 thru V6 and a balanced ECC83S for the phase inverter in V7. Scorchin! The default power tube selection is a matched quad of JJ 6L6GC's in a warmer grade to accommodate the fixed bias power section. With the customize option you can configure this kit to use a range of other power tubes including integrated options. All configurations are hand picked to function with the specific fixed bias Simulclass topology of the Mark V. If your Mark V is a combo amp then please let us know in the comments section and we will ship your kit with the special Double Mica 6L6GC’s which will greatly reduce any tube rattle.