I saw this unit while looking in a motorcycling magazine. It mixes two audio sources (ie both coming out the speakers at once) and provides automatic volume control based on ambient noise. I haven't spoken with the technical guy (he was out) but it looks like a promising product for those of us with GPS & voice turn instructions.

http://www.autocomamerica.com/store/details.asp?intProdId=22756&intCatID=890&intPageNumber=2&fldStoreGUID={0A3DA82D-E6B4-4719-A393-497CFEF75ED4}&fldCartGUID=&strSearchString=&intSearchField=

I'll post details on what I find out tomorrow (when the tech calls me back). Anybody used one of these?

-Zeke

I spoke with Rick from Pro Gear about the AVM unit this morning. The unit will mix two audio sources (via 1/8" stereo inputs) but puts its signal out on a 5-pin DIN connector that nominally feeds headphones. He said that the signal may be too high for line-level inputs into an amp, but he also said that the nominal voltage is 4V, so perhaps not. Connecting the AVM to the 12V on the car requires a power converter (their part PS-90 $59). The base AVM is $119.

I have a two-headunit install with the Sony switch. I thought I would take the amp-on line from that, split it and run one end into a Rat Shack relay that connects to permanent 12V so the unit would come on any time either head unit was powered up. Since it does only two channels I was going to put it in-line between my HU switch's front outputs and my front 2-channel amp. Pro-Gear said they'd supply me with the pin-out diagram for the DIN connector so I could make a connector (or see if I can buy one, Pro-Gear doesn't carry the critter).

I'd run a 1/8" stereo wire directly from my IPAQ (or other GPS) directly into the other input.

I'm told the automatic volume adjustment really won't do much as its set for motorcycle ambient noise, which is much higher than car noise. I asked if this could be tweaked and the answer was "only a little", but that they'd do that for me. Perhaps with windows open at 80mph it might help some.

I figure this will fail if the outputs of the AVM really are too hot for the amp's inputs. Can anyone tell my other ways this might fail? Since my install is so far outside of 'normal' for them that they won't allow a return.

-Zeke