Manley Jumbo Shrimp upgrade

Agree with chayro on this.  I would have offered to do the technical work if you knew exactly what needed to be replaced.  We could always look at upgrading any electrolytic caps, but this is minor.  All the wiring and board lay-out on this preamp is already very good, unless you want to look at putting in OCC copper chassis wire.  The hard part comes with replacing the film/foil signal capacitors.  Since it's a tube amp, a lot of the capacitor choice has to do with voicing the preamp and you could make the preamp better or worse depending on what you replace.  I actually have a lot of experience with solid-state preamps and have a good idea of what works and what doesn't.

Thank you for insightful responses.

Synergistic Research BLACK Quantum Fuses

Celtic66.
1 The Jumbo Shrimp main voltage fuse is a 600 ma slo blo. If you don’t find improvement (or very little) you can return the Synergistic Research Black fuse.

2 You have three tube types to manipulate, 12AT7, 5670 and the 7044.

3 Your output stage capacitors are MIT/Multicap 30uf x 2 total.
I’d proceed in this order one step at a time.

The fuse can make a very noticeable improvement in some components. It’s worth a try.
Charles

Fuses are not part of the active, tone producing circuits in any amp, and are simply designed to allow current to pass through them and fail immediately if necessary to save the circuits from frying. Although SR fuses have a cult following with astonishing claims of transforming the tone quality of amps, I've tested these (SR Black) and found these claims to be nonsense, even while providing the weeks of break-in (!). In fact, after my little comparison to the Littlefuse (and other generally stock fuses) products I've used for years, I discovered an SR Black had been left in my amp for months, which I replaced with the original  Littlefuse with zero change in tone. Try asking anybody how these little graphene enhanced seriously overpriced tiny wire devices actually work (magically coat the electrons with Special Sauce?) and prepare for scorn. The SR business model seems to be "money paid equals results experienced" even when the products are laughably unnecessary.