AVN2 Pre Out & Sub Out Cables?

  1. My model of MX-5 is: __ 25th Anniversary Edition
  2. I’m based near: __ Rotherham
  3. I’m looking for technical help or recommendations on:

I have the original AVN2 (Alpine INE-920W) head unit in my 25th AE. Having updated the firmware to the Alpine version, the sound is pretty decent. Being a music lover, and using the car as a daily, I’m keen to upgrade the sound. I’ve bought a small JL Audio subwoofer which I’ll be installing (yet will be easily removed if needs be) in the passenger foot well. I have found a suitable amp which I can install in the glovebox, and have the option to either buy an accessory cable to tap into the high level speaker outputs on the existing wiring loom, or source a dedicated “Pre Out & Sub Out” cable.
Has anyone else done this? I have found discussions on adding a rear camera using the search function, but nothing related to sound outputs.
I have found this: Alpine INE-W920R INEW920R iNEW920R AUX IN & OUT Pre Out Lead PreOut sub Rear Out which looks ideal (and preferable to the wire tap approach), but would appreciate any advice before proceeding, if anyone has any experience???
The subwoofer is only 6.5", and is just to add some low end weight to my music, not let the whole world know I’m coming :sweat_smile:
The whole installation should weigh about 5kg, so won’t be noticeable when driving :crossed_fingers:
Thanks in advance for any advice / suggestions / input!
Cheers
Nick