'02 GMT800 Burb - new audio vs. YE9 Matsushita 'amp'


Original poster
May 26, 2023
Poznan, Poland
Alright guys, would appreciate you throwing your three pennies here.

I got the 'uplevel' audio system on my 2002 Suburban (RPO YE9), which means six door speakers, two pillar D speakers and one subwoofer in the driver's side cargo trim panel, no rear seat controls.
Someone yeeted the stock head unit a long time ago and put in a tacky Pioneer 1-DIN. Of course the thing sounded like garbage. I decided to replace the HU with a Sony XAV 8050 series (rocks Android Auto and Apple Car Play), had to work really hard on reconnecting the stock vehicle-side harness. Also wired myself a Metra-connector based harness to bypass the Matsushita amp and drive the door speakers directly with the high level outputs from the Sony HU (leaving only the inputs going into the amp to drive the pillar D speakers and the subwoofer.

I did wire the amp trigger wire correctly to the Matsushita amp; there is continuity from the HU side to the Metra connector pin A5 which goes into the Matsushita amp. No joy, the amp won't drive the pillar D speakers and subwoofer (which I replaced, cuz I know the stock sub is trash... and it actually was trash, the membrane was torn out, LOL).
Without further ado, I figured out the Matsushita 'amp' is a passive unit and basically, a deamplifier (boosts volume, makes sound depth crappy). I can easily hook up a new amplifier, like a Sony XM-S400D (Class D) to drive the door speakers (the diagrams list the front speakers as dual, hence six in total in all doors, but they are actually a pair of two-channels speakers (tweeter + mid/low range). I'd use another amp, a simple two channel unit, to drive the subwoofer. The Sony HU has five line outputs (RCA), which means front and rear L/R channels and one subwoofer output.

This leaves me with having to figure out how to wire the two pillar D speakers (in the factory audio setup, they are kinda like mid-range 'presence' speakers that fill out the cavernous trunk with sound for the 3rd row occupants to enjoy music.

1. Can I safely wire the door speakers over RCA cables to the Sony amp, the subwoofer over an RCA cable to the second (2-ch.) amp, and then use the high level outputs of the Sony HU (rear left/right channels) to drive the pillar D speakers at the same time? I figure it is safe to use all line outputs (RCA) and the RL/RR high level outputs at the same time?

2. Can I just disconnect the Matsushita amp and yeet it? The diagrams show it only drives the speakers and was wired to the stock CD player (which is, surprise surprise, gone); so I figure it doesn't do any funky stuff, like driving the dash chime (like on the 1990s Cadillacs).

3. Location for the 2-channel amp to drive the subwoofer: this unit is a big boy. The size in plan is just a wee under the size of A4 sheet of paper. It won't fit beneath the glovebox, nor will it fit under the driver's side part of the dash; I know people just stick amps below the cupholder insert in the center console, there's access from the front of the center console to do that. I figure my center storage cubby is too big, it's deep and probably touches the brace between the console and the floor hump over the T/C/driveshaft.
I don't want to put that amp beneath the driver's side panel in the trunk; the car has a CB installed and the excess of the antenna cable is secured 'snaked' to the inward face of the trim panel; don't want any interference from the amp's high power components anywhere near the 3-4 zigzags of snaked antenna cable. Any ideas for a better place to install the amp?
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Lifetime VIP Donor
Supporting Donor
Oct 22, 2015
Tampa Bay Area
Try Shadowing the Dude in THIS Suburban Amp & Subs Installation ...just to compare whatever he does here with whatever your installation procedures were ...and see if he did any things differently from yours that might help you out.

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