Just need to add some warmth and definition? This is our Standard Retube kit for the Dr. Z Maz 38 Heads and Combo Amps. It includes a matched quad of the JJ EL84's for power, a JJ GZ34, one ECC81 to replace the 12AT7 along with four ECC83S's with one being current balanced for the phase inverter in V5. 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.