Tube amps - what 3 things…

My Firebottle is from late 2016 (it has its birthday on the bottom with Had's signature) I and  bought it in early 2017 for 1100 bucks or so. I'll never sell it.

Hidaleeho.  Having computer troubles, so just seeing the status of this thread.  Good exchange of info...good.  Ralph, I'm sure that I'm wrong because I'm even more sure that you're right.

Got some 8 Henry chokes on the power supplies of the amps at chez xeno, and wow, they're lurkers.  Carry on...

Cathode bias is not a good thing in input and driver stages, not just in the output stage.

I tried one solution in my DIY SET 300B amp. There is 6sn7 input tube and 6F6G in triode mode driver tube with coupling capacitors between stages. The solution is very big, around 100000uF cathode capacitance in the input and in the driver tube. It gave a huge improvement in everything: bass, soundstage, separation, high resolution.
It is a pity the same solution can't be used in the output tube cathode, because of high current start-up issues. The Maximum capacitor I can put in my 300B cathode is 5000uF. It improved sound but it can't exchange fixed bias in terms of SQ. 

Cathode bias is not a good thing in input and driver stages, not just in the output stage.

I tried one solution in my DIY SET 300B amp. There is 6sn7 input tube and 6F6G in triode mode driver tube with coupling capacitors between stages. The solution is very big, around 100000uF cathode capacitance in the input and in the driver tube. It gave a huge improvement in everything: bass, soundstage, separation, high resolution.
It is a pity the same solution can't be used in the output tube cathode, because of high current start-up issues. The Maximum capacitor I can put in my 300B cathode is 5000uF. It improved sound but it can't exchange fixed bias in terms of SQ. 

@alexberger I've yet to see a voltage amplifier or driver circuit that isn't cathode biased. When a cathode bypass capacitor is used, its still cathode bias. Its not cathode bias when you have a manual bias adjustment to make, or the amplifier is employing some form of autobias (both are forms of 'fixed bias' since the bias adjustment is made via the grid).

I've read controversy around the sonic differences between cathode bias and fixed bias but IME its really about design and how well the circuit is executed. Both types work just fine.

@atmasphere 

+1