Sounds similar to my experience.
I await delivery of what will become the third 0 AWG cable driving my speakers.
I found a clever way to couple two cables and a tail for use with a banana plug, see: https://www.amazon.com/gp/product/B07QZRKXSL/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
The above linked battery cable coupler comes with a clear plastic snap-on cover for insulation on four sides. The remaining open sides can be protected with electrical tape. I use a 60 amp ring lug terminal connector, secured to the battery post bolt with the lug positioned in the slot on the coupler. This lug is crimped and solder to a 6 AWG 2" tail that connects to the banana plug.
My third 0 AWG cable will be connected to the amp via a tinned wire tail inserted in the screw clamp connection on the amp. The bananas connecting signal to two of the 0 AWG cables are connected to same screw clamp. The screw clamp has a female banana plug connection at the end of the clamp tightening knob. This arrangement allows me to use two short tails per tap to reduce resistance.
At the other end of the three cables (total of six per side) I attach a 4 AWG 2" tail with a 30 Amp ring lug for connection to a terminal board that connects to the crossover.
I will let you know if the third cable install improves the sound.
The fun continues.
Very truly yours,
J