Yeah, I just recently read in another PS2 thread that setting the switches flat pretty much defeats the reactive load.Even if you tweak the switches?
Switches set to FLAT completely eliminate the reactive behavior of the load as it relates to the amp under load.
What remains is the subtle reactive behavior between the PS power amp stage and the speaker, which can be accentuated using the Presence and Depth controls, and in some applications can produce just the right amount of feel. By "some applications", I mean where you want to eliminate the really obvious load reactance and instead apply a very subtle sweetening. That will vary depending on amplifier type, playing volume, amplifier power output, etc. We find for example that players with medium powered BF Fender amps tend to like the switches set flat. This might be because Fenders are already pretty scooped and crisp on top. Setting the load to Flat smooths the amp out a bit.
Read little while back Carl @fusionbear saying how the TW Express circuit doesn't work as well with attenuation. Pretty interesting findings.
This calls for MOAR TWEAKING. It shipped with all TADs so I have some on order, but a previous owner of this amp contacted me and suggested Amperex power tubes and a boxed anode Mullard CV4004 in V1.