Want all the gain you can get? This is our High Gain Option Retube kit for the Dr. Z Prescription Junior Heads and Combo Amps. It includes a matched pair of the JJ EL84's for power, a JJ 5Y3S, an EF806 for V2 along with two Handpicked High Gain ECC83S's with one being current balanced for the phase inverter in V3. Mike recommends a JJ gt #6 for power but since we have 30 different grades of the JJ EL84's and we know where the bias point is on these amps, just let us know in the comments section if you're looking for an early breakup, a moderate breakup or a later breakup for more headroom in which case we will choose the coolest grades we have available for the power tubes.