12AX7A preamp tubes - ribbed vs smooth plate

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.

@jond 

You got lots of cool stuff. Maybe you have too many tubes in boxes. Why you have so many tubes?

4 12AT7 tubes. no clue what they do Beyond rectify. I know rectify transforms AC to DC and why you need four tubes to do that, dunno.