Want a really rich and smooth tone with less grit? This is our Gold Pin Option Retube kit for the Dr. Z Prescription ES Heads and Combo Amps. It includes a matched quad of the JJ EL84's for power, a JJ GZ34, a Gold Pin EF806 for V2 along with two Gold Pin 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.