I summarized Pro's and Con's of Bi-Wire and Bi-Amp [incl. TRUE Bi-Amp] in fol. post, which you should read.
In 1971 I bought my [now Vintage] ALTEC Voice-Of-The-Theater Speakers (15-in Woofer + 800-Hz Horn with Compression Driver) and about 1975 bought a Marantz 250 Amp (125 wpc into 8-ohms) for a Quasi-Bi-Amp configuration, retaining the VOTT's Crossover for the Tweeter driven by a Dynaco 120 Stereo Amp [cuz minimal if any improvement with Active Filter] and built my own DIY L-C Low Pass Filter for the input of the Marantz 250, BYPASSING the ALTEC Crossover for DIRECT DRIVE of the 15-in Woofers [Re=10-ohm, Bass Reflex QB3 Alignment, as per my Thiele/Small Measurements & MANUAL Calculations]....with a 32-Hz Bass Boost "Step Roll" R-C Network added to output of Dynaco PAT-4 Preamp (later Soundcraftsman Preamp had separate Octave Band Filters that did same thing). As expected, there was a noticeable improvement in Bass Transient Response and clarity, so the significant improvement in Damping Factor was indeed working.
Much later I repurposed the ALTEC 15-in Cabinets to act as a pair of Sub-Woofers (only), closing off the Bass-Reflex Vents so it was a Sealed Cabinet [so Critically Damped Transient Response], which provided another improvement in Transient Response, eliminating the "thump-ata-bump" drum echo typical of Bass-Reflex Alighment (see my Loudspeaker Comparison Post).
In 2006 I bought my current AVR, a Pioneer VSX-1015 AVR with PRE-OUTs (120 wpc into 8-ohms, with High Power MOSFET's for better Transient Intermod Distortion), which soon thereafter I configured into another Quasi-Bi-Amp configuration to drive the L/R Speakers. I repurposed an old AVR [100+ wpc] to drive the 10-in L/R [Sealed-Box] Woofers, using a Second Order Filter to Roll-off the High Freqs on it's Input (driven by Pioneer L/R Pre-Outs). And the Pioneer AVR drove a Passive DIY Second Order [700 Hz] Filter connected to the Bi-Polar Planar Magnetic Mid-Range and another higher [7 kHz] Crossover to the Ribbon Super-Tweeter [same Passive Crossover as my DIY Center Speaker]. So with Sub-Woofer turned down, I can clearly hear an improvement in the L/R Woofers when AVR set to "LARGE"....and not as much if set to "SMALL".
So if your AVR does NOT have PRE-IN as well as PRE-OUT capability, you might want to consider trying my Quasi-Bi-Amp Configuration, perhaps using a Commercial Active Low-Pass Filter on the input of the new "Woofer" Amp, so you only need to open up the Speaker Cabinets to disconnect wires from Internal Crossover to the Woofer and rewire so "Woofer" Terminals connect DIRECT to the Woofers.
I'm an Engineer/Scientist who prefers DIY when I can, so I don't have any particular Active Filter or Crossover recommendations. There are several Pro-Audio Active Electronic Filters (mucho $$$'s and typically Rack Mount), but you'll likely find affordable products intended for CAR Applications....which means you'll also need to buy a suitable (voltage & current) Power Supply for it, such as the fol. examples which are inexpensive and loaded with Features you may never use:
[Pro-Audio Rack Mount]
[Pro-Audio Rack Mount]