Filter Caps and Sag on a Champ 600

[Gizmo]

hey yall

So I'm finally going at my Champ 600 my planned mods are pretty straightforward and run of the mill:

-Weber late-breakup 6in Alnico speaker
-switchable tonestack/coupling cap (black/tweed)
-switchable neg. feedback

Here's my question: I'm also thinking of going at the filter caps, but I'm still learning... some people seem to report better low end response with beefed up filter caps, especially by upping the first one in the B+ to 40 (frpm 22uF), then dropping the preamp filter to 16 (from 22uF). Sounds good by me, but I really dig the compression/sag I get out of the amp stock when wailing on it with p90s... will I loose that by beefing up that first cap? (or am I even hearing sag in a class A amp?) Can someone give me a quick tutorial on filter caps and tone?

[Gizmo]

Further thoughts:
‎
here's what I think I know. Tube circuit - bigger filter caps will increase the B+ supply (power to the plates). Also, at least in AB class amplifiers (push-pull operation), smaller filter caps will cause sag/compression under strong signal.

My specific application: I am trying to increase gain and headroom on the 600. At the same time, I'm getting a great compression out of it. I think I might just have to up the filter caps from the transformer but lower the one feeding B+ to the preamp in order to restore some of that compression, which would be in keeping with that recommended first cap to 40uF, pre-amp cap to 16uF.

Is that reasoning sound?