What should I prioritize to upgrade next?

My current car is a Subaru Outback with the non-Harmon Kardon Starlink infotainment system. I'm looking into ways to upgrade my setup. My current disappointment is with the crossovers points and phase alignment between my subwoofers and door speakers. For the crossovers, I've set 80Hz for the door speakers and ~60-70Hz for subs. I still get a lot of bleeding between the two due to the KEY200.4 amp having a -24dB/octave slope and the two subs using a -12dB/octave slope.

I'm thinking the only way to fix the sound quality is to implement a Helix DSP and disable the Key200.4's DSP. Let me know if there's something else I should look into.

Current Setup (using my factory radio):

Front 2CH Factory Radio Out ->Kicker 47KEYLOC

• 1st Kicker Key 200.4 Amp (Biamp Mode)
  • (Dash): C1-100ct Tweeters
  • (Front Door): C1-690cw Woofers
• JBL Club A600 mono sub amplifier
  • (Spare Tire Compartment) JBL Stadium Basshub
• (Under-seat): Kicker 51HS10 subwoofer

Rear 2CH Factory Radio Out

• 2nd Kicker Key 200.4 (4CH Mode)
  • Rear Door: Focal RCX-165 Auditor Series 6.5"