Look, I'm going to give you a real easy guide to the Bogner Ecstasy:
The absolute best amp in the world is the Ecstasy 20th Anniversary with 6L6s. Just accept that as fact for now OK. The 101B was like Sith Vader who ruled for 20 years or whatever, then the 20th came long like Darth Vader and became supreme commander, or something like that. Then there's the highly regarded 101A which has a magnificent sound, and the people who love it really, really love it, but they're rare. Personally, about the only thing that struck me as different was the clean channel and everything else was kind of just the same as the 101B.
If I'm not mistaken, the 101A was the primary inspiration that contributed to the development of the 20th Anniversary. Well, more recently the 3534 came along and sort of embodies the 101A but with with the 101B blue channel. Aside from having equally incredible tone, the main advantages are versatile volume levels and more accessible price point.
Now there's a brand new XTC which I don't remember the name of. I don't know much about it, haven't even seen one in person, and all I really know is it's really expensive. I can't tell you much about it.
My experience? Well, I owned all of them. I had a 101b for many years, got an incredible deal on a 101A and sold it like an idiot, bought a 20th Anniversary on credit so ended up selling it to pay off the debt, got another 101b, but eventually sold it and have been using the first 3534 shipped to Guitar Center since. So I have travelled the XTC road and never found my way off of it. They're the most incredible sounding and feeling amps I've ever played.
You can't go wrong with any version so don't be afraid to take a chance on any of them. I know a guy who has like a 16 year old 101B, still all stock and unmodified, never needed any kind of service or repair, and he still uses it all the time. They're seriously that good.
Quick note on the 20th Anniversary: there are some who swear it's 'better' with EL34s but I have played both and that's simply not true. In fact, Bogner designed it specifically around 6L6s. Honestly, I almost got conned by the conviction of those EL34 dudes but when I spent a few weeks playing one, it just sounded like something was missing. It was like going home to an perfectly identical house but knowing it's not the house you left to work from in the morning. Seriously though, if you're like an EL34 or nothing guy then you'll like it better with EL34s. Personally, it's best with 6L6s.
I've spoken a little in jest and hyperbole so take what I said lightly in that regard. However, there are a few things I think kind of underlines each version:
The 101B's blue channel is unbeatable
The 101A's clean channel is stunning
The 20th's red channel is what dreams are made of, but it also takes the cleans of the 101A and blue channel of the 101B and kicks them up a little notch
The 3534 is like 101A cleans + 101B blue channel + 20th red channel. It's smaller and has only 2 EL34s, but has a full low end and lots of punch.
The one thing you might want to look into is the effects loop. Maybe this is just me but Bogner FX loops can be very picky and may need a little effort to get right. I've owned the GF90, Metropolis, Duende, Uberschall Rev B, and the aforementioned Ecstasies, and in my experience, the FX loop needs quality cables and some volume also. I don't think they're particularly great at low volume. I once called Bogner about this, spent days trying to figure out what the problem was, I think the guy's name was Charlie, and he said you need to use very high quality cables. In fact, I used to use my good quality cables for instrument and speakers, but wasn't very discerning about FX cables, so I replaced all my FX cables, patch cables, and got a high quality power source for my pedalboard. This cured the problem.
Well, this is my opinion from my own experience. I'm sure some may disagree on a few things but I think I gave you a decent rundown. Hope this helps man.
