Well, my designs have evolved since the RH807, and I feel that those still using their RH807s might check out the RH84 rev2 - they might implement some of the proposed improvements on their amps.
The RH2A3 is a direct derivative of my RH300B work, thus it has inherited the additional cathode follower tube. It was not strictly necessary in the RH300B, and is even less necessary in the RH2A3... but it helps the driver tube and does indeed impart additional bass notes quality.
I do not think that implementing one additional tube in CF configuration is difficult for the DIY-er: after all, it is directly coupled to the driver tube, and besides the socket, one just has to install two resistors (I am not even counting the two grid stopper resistors, since those are actually good replacements for pieces of wire one would have to solder on anyway). The only thing to watch for is cathode-heater differential, as it should be lifted ideally half way between ground and the CF cathode voltage - but that is easily accomplished with a voltage divider, which serves as well to discharge the caps once the amplifier is turned off.
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