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.