[hahtbites]

I just tried this scenario of trying to save the HU. I was very skeptical of this approach as I couldn't understand why the HU would be any better than the rest of the system.

My setup included:

Amp: JL Audio 300/4
Front Components: Polk Momo MMC 6500
Wiring: Rockford 4 Gauge power, JL 16 Gauge speaker, Rockford Twisted pair RCA spliced into low voltage output from HU(As suggested in this thread).
I faded to the front channels so that I only heard the new speakers.

My findings:

First of all you won't be happy with it if you've ever used an aftermarket HU such as an Alpine, Kenwood, etc.... I'm not talking about features. I'm talking about sound quality. I tested this theory by connecting an old Alpine HU that I had from a previous car. There was no comparison. My suggestion is that you only do this upgrade if it's a stopgap until you can afford to replace the HU. I personally think it sounds awful. If anything the upgraded amp and speakers bring to the surface what could not be heard with the stock system. I plan to connect my iPod directly to the JL until I can afford the HU conversion. The iPod's signal is much cleaner than that of the HU. It should come as no surprise that the entire Infiniti/Bose system is junk for the masses as most stock systems are.