Is bi amping worth it ?

No, it really was not worth it in the end. 

Tried it several times and a few ways, with the same of each amp. Vertical and horizontal configs. It could sound "exciting" at first, but never convinced me to stick that way for longn. Seemed less musically coherent somehow (there can be slight differences in units of even the same model of an amp). Not good results with bridging SS amps to mono, either. What I didn't try is biamping with disparate amps (like tubes up top) - but honestly the coherence issue when biamping with the same SS amp turned me off that idea.

What CAN make a big positive difference is taking two stereo tube amps that can be switched (paralleled) into mono, and running them as monos. 

This was done with Tannoys that are relatively efficient. 

Three ways to improve your base I can think of...

1. Call Greg at Volti Audio and ask about upgrading your driver and/or crossovers.

2. If you're streaming music, get a streamer that has EQ.  I use Eversolo w/o using their DACS - just straight stream, but their EQ in their app is easy and excellent.

3. Dual quality subs that have crossover adjustment.

I integrated a pair of REL Carbon Specials w/ my Volti Rivals (using McIntosh C2700 tube pre w/MC462)... Set crossover fairly high so mid-range voice comes through.  Is unbelievably good.  Adding well integrated subs improves presence, warmth, makes the soundstage wider and deeper, and when you get it right adds a rich holographic overtone.

But Klipsch bass driver loose/flabby - would clean that up first, then think of next step.  Call Greg.

if you do wind up looking for an external crossover, this is the one I would look at. All analog, no digital in the signal path.  I don’t have personal experience with it, but I have researched it a good bit, and found positive reviews.  if you do wind up getting one, DM me with your thoughts on it.

https://sublimeacoustic.com/products/k231-stereo-3-way-active-crossover

45 day return policy. Their FAQ section is helpful.

Gemoody 

that looks like the perfect crossover  . Inexpensive enough to give it a try.  
 

namrider1 

I did reach out to Greg last year when I had vintage khorns .  Were going to upgrade all Component’s with volti and then I can across an opportunity to trade my vintage horns in on a new pair of horns and did that.  The new enclosed horns were much improved over the vintage , especially the bass.   Not looking to upgrade these speakers ( as yet )   
 

I see where if you buy direct from REL they give you a 60 day trial.    I may try a set of the classic 99 . I admit I like the way they look cosmetically ( already have a large  black box subwoofer for theater)  just hoping they will add enough.   Seems two of them should. ? One to each mono block