12AX7A preamp tubes - ribbed vs smooth plate

@immatthewj amps use a variety of small signal tubes in their inputs it's also possible the OP is referring to an integrated amp.

If this is the same amp(s?) that OP was referring to a while back ago with (I think I remember him saying) 16 output tubes, I wouldn't think it would be an integrated.

It's a mono block amplifier with 8 KT 88 and 6 small tubes (  4 rectifier, 2 preamp).  And in this food chain, it's my understanding the 2 preamp tubes probably impact sound the most.  So this is where I want to spend my money.

@emergingsoul Is this the amps you have here?

Mike

"It's a mono block amplifier with 8 KT 88 and 6 small tubes (  4 rectifier, 2 preamp)"

Huh?

That's a most unusual topology.

What brand is this? Dual rectifiers for each channel?]]

I doubt there are 4 rectifiers that doesn't make any sense.