Please excuse my not understanding what you are trying to accomplish apart from 'improve the sound' - could you say a bit more about your goals or what you think is a weakness of your system?
Changing dampers may help smooth out small tube noises, effectively lowering the noise floor. That is, if your tubes are noisy to began with. The Herbies dampers do work, but they will not be to the level of a component change. The 6H30 tends to be a v. quiet tube, so I doubt you'll hear much improvement going from the stock silicon ring dampers to the Herbies. YMMV
Switching from 6H30-EB (stock) to NOS 6H30-DR will not, imo, make a lot of difference in the ACT2. Maybe a wee bit more top end extension, though I'm not entirely convinced of that and I'm running 4 NOS DRs in my own.
The original ACT and the 2.2 are dynamically adept preamps. As you imply, they may not reveal all their virtues in a few hours. There are lots of gears that stand out with one or two sonic attributes, but very few are well balanced across the spectrum. The ACT2 and ARC Ref3 are a couple that fall in the latter category - there are others. I've never heard the Diva M7, so cannot speak to it.
Tim
Changing dampers may help smooth out small tube noises, effectively lowering the noise floor. That is, if your tubes are noisy to began with. The Herbies dampers do work, but they will not be to the level of a component change. The 6H30 tends to be a v. quiet tube, so I doubt you'll hear much improvement going from the stock silicon ring dampers to the Herbies. YMMV
Switching from 6H30-EB (stock) to NOS 6H30-DR will not, imo, make a lot of difference in the ACT2. Maybe a wee bit more top end extension, though I'm not entirely convinced of that and I'm running 4 NOS DRs in my own.
The original ACT and the 2.2 are dynamically adept preamps. As you imply, they may not reveal all their virtues in a few hours. There are lots of gears that stand out with one or two sonic attributes, but very few are well balanced across the spectrum. The ACT2 and ARC Ref3 are a couple that fall in the latter category - there are others. I've never heard the Diva M7, so cannot speak to it.
Tim