Sub recommendation to augment Klipsch La Scala's ???

If i can find another sub like mine I might just do that too...I have Heresy III and they sound great with my sub , but one sub can't really keep up as the volume increases... its tricky to find the right level for a single sub

What ever you do get one with an internal crossover build in. It will make thing cheaper and easier. 

Sadly very few modes have this feature. JL e line or subs does. I am sure there are others too. 

How I wish I had that kind of room again. A pair of Lyngdorf W210’s would be perfect, in that situation. They certainly sell quickly! https://www.audiogon.com/listings/subwoofers-lyngdorf-tact-audio-w210-subwoofers-pair-wood-veneer-la... and https://www.canuckaudiomart.com/details/649360945-tact-w210-subwoofers-lyngdorf-w210-subwoofers/imag...   More: https://www.avforums.com/threads/lyngdorf-w-210-corner-boundary-woofers.2048562/

I remembered reading this a while back. Not cheap when you add the amp/crossover, but maybe you can get some ideas from someone who had to figure out the same problem you are having.

http://www.voltiaudio.com/vittoradesignnotes.shtml

@ m-db
The B-15'd were not in the corners but I am going to make another run at them this next weekend.  I think I may have over EQed then using my RTA software taking out the impact at the leading edge of low notes which presents as slow or smeared.  Regarding connection configuration I did not use "Y" connectors but was considering it this time around.  I want the La Scala's to run full range direct from the Coincident Franky-II's and my PS Audio BHK pre only one set of outputs.

@ acman3
Great idea!  Funny I spoke to Greg at Volti just the other day.  That would be a great solution but much too expensive at present.  I looked at his complete system last year and even found one on the used market for $15k but just out of reach when I could get the new La Scala's at just under $8k.