With the front speaker upgrade finished, it was on to the rear doors. For the rear I went with the same company (Hertz), but since the rear was mainly for when I have passengers in the back seat (which isn’t often) I went with a pair of Hertz Audio DCX-165.3 coaxials. Whereas swapping the front speakers out took less than 30 minutes, the rear doors were a different story: since I didn’t touch the rear door at all during the first audio installation (other than the Dynamat), I had to pull the B-pillar trim panels to access the B-pillar area, and then fish new speaker wires through to the rear doors. This turned out to be a lot easier than I expected since I had a straight shot through the wiring loom tube (unlike the front where the loom enters the cabin up under the dashboard).
Another thing about the rear speakers – although I installed them at the same time as the fronts, I couldn’t use them yet! My Alpine main amplifier has 5-channels; 1 and 2 are wired to the front dash tweeters; 3 and 4 are wired to the front door woofers; 5 powers my two JL Audio subwoofers. The OEM rear speakers were powered by the Kenwood head unit.
To run the setup I wanted, I had two choices: find a good 7-channel amplifier that put out the same power in the same small, compact size that the Alpine PDX-V9 had (not likely), OR I could add a separate, smaller output amplifier to the current setup to power the rear coaxials. I decided choice 2 made more sense – so while I enjoyed the sparking highs and excellent kick from the new Hertz front components, I knew that the next step would be to find a small 2-channel amp. Not only that, but it would have to be small enough to fit under the seat next to the TWK-88 somehow.