I haven't looked at the Akido design lately. I was wondering if the second 6SN7 is a cathode follower? If it is, it might be fun to somehow install a switch where you can switch out the first 6SN7 gain stage.

I owned a VAC preamp several years ago that had switchable gain stages that used 12AX7's for the gain, and a 12AU7 for cathode follower. Switching out the gain stages all together was my preference, but had a slight negative gain. As with all components in the signal path, they introduce their own signature.

Keep us informed of your progress?

I am very curious of how well your 2 watts will go towards driving the Four Pi's?
I will be building a 2.5-way version of the Four Pi using 2226J's with Beyma CP-385ND 1" CD and TD-250 horn.

I am hoping two watts will be enough to get them a rocking at 100db efficiency.

Have fun!

NW