It's the head out of the Coda+ into an Acme B2 (4ohm). A great rig at club level but on bigger stages I need to move more air without whining for more foldback. Was thinking of adding another B2 but now I'm thinking a 4ohm quad or even some kind of fridge.
You are probably pushing close to the limit of feedback on your bass already I'd bet. That's a good sounding low efficiency cab there that will suck up all the 800 watts of power you have and deliver good sound but at a lower volume than you'd get with a higher efficiency cabinet. It's 93db at 1W1M from a 210 box. If you like Acme sound the 410 may do what you need however it's only adding 3db to your sound in a close to the floor arrangement.
I'd suggest that you may like a pair of the 210's on top of each other using a pair of the 8 ohm versions rather than a pair of the 4 ohm versions. The amp is rated at 800w at 4ohms and 1000w at 2 ohms...not much of a difference if any AND the tone of the amp suffers at that load. That should be more than enough juice at 800w at 4 ohms for any gig though.
Might, if you can, demo using a pair of the 4 ohm versions and see how it works over a night before spending all the dough but I suspect the amp will get to hot being that loud at that low of an impedance pushing that low efficiency speaker all night. The stacked array of 210's gets your speakers up higher, closer to your head so you can hear yourself better. Gives you an extra 3db of gas at that same power level plus something for coupling and it won't stress the amp any more than it already is. That should be plenty.
Some other thoughts:
If that rig you have already isn't getting your heard in the room without PA support the band is to loud and should consider PA support if you want to be that loud. If that rig you have already isn't getting your heard in the room AND you have PA support, you have a FOH engineering problem not a stage monitor problem. If you are fine now in the room but can't hear yourself onstage or the bandstand mates can't hear you they might be playing to loud or the ensemble is spread to far apart. That's a logistics or personnel problem, not an amp support problem.
Regardless I prefer my speakers to array vertically rather than across the floor so I get a speaker up closer to my head. Helps me hear what I am doing better without getting too loud on the bandstand and moving into feedback land.
Be sure your bass is tuned up well and your pickup is functioning at it's best.
Mostly I'd be sure I'm getting all I can from my bass. Be sure you are pulling a good loud sound from it and not just playing softly and using an amp to try to get real loud rather than pulling a good loud sound from the bass and using the amp for support.
Lastly I'll say that's already a lot of amp for a double bass. You'll very quickly move into diminishing returns from where you are...to the point where an EUB or something else might be more appropriate. I usually ask everyone else to respect the volume limits of the DB if they want that sound in the ensemble. You can only get so loud with the thing before it gets unmanageable.
