I'd be surprised if you could get this to sound right anyway. I haven't looked further into it, but I suspect that you're not just dealing with a different line level, but different load (amps) too.

The monsoon amp is 8 channel (very nice, but rare), and that may have some affect on how it is driven.

However, if this works, I'm interested, because I'll have to either do this for my Passat or have the whole thing rewired with new amp and headunit.

I haven't installed yet, but right now my workaround will be to use an RF modulator to plug into the radio antenna. I'll let you know how the quality is, but I bet it will be fairly good with the powered antenna.

You can probably get some of this info from www.clubb5.com (Passat board, but same problem anyway)

-Joe