Options for aftermarket audio upgrades

[willyworm*]

I've had my E70 for just a couple weeks now and I'm already missing my subs and decent (by my standard) mid and hi range sound. I've been doing lots of reading and replacing the head unit is not an option I'm willing to explore at this point. There's really no need to replace anyway if I can add premium sound to the existing system.

I got my start in electronics by my interest in car audio. So I'm pretty good with stuff but I'm never tackled a bimmer. So after consulting with a few friends who are still in the biz I stumbled across Wavtech equipment. Rumor is it's a relatively new company, which makes me skeptical, but the guys heading up this venture are former head guys at Scosche and Alpine. www.wavtech-us.com

I have a MTX Thunder 5 channel amp that has been great to me over the years. I've had it in 3 different vehicles and I'll keep it as long as it continues to function. I have my speaker selection figured out, I think, just need to get a gameplan on how to accomplish the install.

My question is, are the lines from the head unit feeding "stereo level" inputs to the OEM amplifier in the rear? I'm trying to tap into an audio signal somewhere to feed into the Link4 to convert to RCAs then into the MTX amp. All the MTX has is RCA level input, so obviously I have to convert from stereo level to RCA to make this whole thing work. This Wavtech Link4 is my leading candidate so far. At $100 it's FAR cheaper than any other option that I've seen out there.

Anyone got experience with the Wavtech, heard of it, or can suggest another option to add aftermarket sound?

[willyworm*]

I failed to mention that my 35d has OEM amp but no back pillar speakers. Just the existing speakers in all 4 doors and center channel, not sure if there's a sub. Honestly haven't looked under the back seat yet, but if I can accomplish this install it'll replace the OEM sub anyway, so it's really a non-issue.