The Devil said:

I also used paper-in-snake-oil coupling capacitors in my amps. They
(as in 'They') *wouldn't* believe the difference. Also Black Gates
everywhere. They might be expensive, but an amp totally free of
aluminium electroltyics is an eery and awesome experience. I have come
to think of any amp that uses aluminium foil power supply capacitors
as broken. Totally broken.

Black Gates? BWAHAHAHAHAHAHAHAHAHAAAAAA!!!!!!!
Listen to this, my friend: An amp is only an amp with MKPs and
paper-oil caps, and each has to have its own place in the circuit.
PIO for coupling, MKP for power supply.
Chokes in the HV and as few uF as you dare.
Check out www.duncanamps.com and download a program called "PSUD".
Play with it and design your power supply with a Q of about 0,6 .

Cathode bypassing capacitors don't belong in class A tube designs.
Neither do they belong in class A valve designs. LOT;s ! ;-)

Oh, and use AC on your heaters. Definitely better, unless you're using
DHTs.

--
Sander deWaal
"SOA of a KT88? Sufficient."