My 2000 s has the 8 & 4 ohm outputs.
Like I said, every 2000S I've had my hands on was 8 & 4 ohms. Just be aware that it
can be or even could have been internally rewired to get 8 & 16.
Can it be wired in series to the 4 ohm taps ?
Sure, you can wire it however you want, but how would you get two 2 ohm loads with your current speakers?
I'll consider your other suggestions as well and discuss it all with the tech. The "Guitar Center" near me (in South Jersey) is supposed to have a semi-retired electronics wizard that knows everything there is to know about old vintage amps and Sunn in particular.
Perfect! You're fortunate to have easy access to an old school amp tech. You should should get them to post on this forum.
Needing different cabs is a real bummer. I recently put about $ 1,100 to get what I have. I guess I should have done more research first, but like I said I didn't know I would be buying the 2000S or even that I would be playing in a band again when I bought them.
You don't necessarily need new cabinets, I sometimes run a Hartke 410XL (loaded with 4 ohm Eminence Basslite aluminum cone drivers) and a Hartke 215XL with a modified 2000S, and it sounds great and gets loud enough for practice or small gigs. Of course “loud” is a subjective quantity. As previously mentioned...
The 2000S is a powerful amp, but it's from a day when a 120 watt bass amp was a monster. It's also from the time, by necessity, of very efficient drivers and cabinet designs. Modern bass amps with 350, 400 or maybe 1000 watts can force a less efficient driver/enclosure combination to strip paint by brute force, a 120 watt amp needs to work with the right combination to get stupid loud.
Which is re-emphasized...
I have a late 60's 2000s and when I first found it and played it, it was not that loud. It turns out, it needed a rebias and one solder connection fixed, and man, what a difference. I do have 2 2x15 cabs with JBL's (D-130's and D-140's) and man, it sounds great. I run my JazzBass near open and the amp on maybe 2.5-3. We never lack for presence on the bottom end and we're all half stone deaf after 35 years playing.
Those D series JBL's have very close VC tolerances and compliant cone suspensions that allow them to move a lot of air with minimal wattage. It also allows them to meltdown or decone themselves if you try to run 200 - 300 watts into one. The D's are rated around 75 watts or so, while the Eminence drivers in your Avatars are rated for 250 watts each. The 215 cabs have a lot of room and ample porting to utilize the front
and back side of the drivers to their best advantage. This also makes them about as portable as a washing machine. Your Avatars will fit in the back of a VW Golf.
With the proper amplification for the specific cabinet, both will make your ears bleed. It's just "old school" vs "new technology", you can blend them but it's difficult to do it indiscriminately. You need to put some thought into it. With big SS amps you can just pile on drivers until your impedence drops below the amp's stability threshold, and with smaller tube amps you need to match drivers to output more carefully.
I'll bet if you get your 2000S sorted out electronically, and hook your 115 and B210 into it, you'll get a satifactory result.
If it isn't loud enough, just get another 2000S!