What can you tell me about First Sound pre-amps?

Yikes! Rackon is correct, I do mean finer increments. I always thought this was an appropriate use of granular, but I just went to the dictionary and see that I'm all wet (or liquid, if you prefer). More steps in the stepped attentuator, how's that? (Not to be confused with having a preamp that goes to 11, which is also a good thing.)

Rackon:

It's possible that the FS and the Valhalla aren't the best of friends, but in this system, it does show up regardless of the interconnects.
Trust me, Artg, I'd love nothing better than for the system to NOT sound a bit hard on brass crescendos. I just don't know what else I could change as every single components, tubes included, has been substituted into the system. It's a bit of a puzzle to me. I wondered if the OA 2 tubes could be going bad, as they're the only tubes I HAVEN'T changed in the preamp!
And, for those considering the First Sound, it is entirely possible that this may be an issue endemic only to MY particular preamp. Not this model, just, literally, the First Sound Presence that I own. And I've read the reviews and I've never noticed anyone mentioning this. Unfortunately, my First Sound hasn't read the reviews, and it seems not to know it shouldn't sound edgy on Forte-level brass!

Mphkns, Here is another hypothesis: is it possible that what you are hearing with FS on loud brass creschendo is what is sometimes called 'cuivre', or 'brassy', which can be heard live, when the metal body of the horn actually vibrates somewhat loosely under extreme FFF. If that were the case it may mean simply that FS is more revealing than other pres. But, if you do not like 'cuivre', you are not the only one. Cuivre sound is the bane of orchestras and conductors, unless it is specified explicitly in the score.

My understanding is that the OA2 tubes are either good or they are not, but they don't go bad over time. Also, as I recently discovered, the preamp works just fine even after they do go bad (or at least after one goes bad). The triode tube doesn't get properly biased is all that happens, so you may start to notice some sonic changes.

By the way, I bought 4 of them from New Sensor and it's a good thing because one of them failed pretty much right away. Apparently the failure rate is high, but if it happens, it's within a couple of days.