I'm the guy who had speaker problems with his 7... To make a story short everyone said one or more bad speakers and further trouble shooting....
Researched it and purchased a used Logic7 from http://www.bmrparts.com/index.htm Bavarian Auto Recycling, one of the largest, most experienced, and most organized BMW recycling facilities in the world -- (over 10,000 BMW's dismantled) Quote from there website... After that everything worked fine.
Replacing it took me about a half hour, It took longer to get everything out of my trunk. Hot swap. no programing and you'll be good to go...

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2006 BMW 650i Sport/Premium Package
Mods/Upgrades - Spacers, AC Schnitzer Pedals, AC Schnitzer Mats, 21" BMW 128 Rims, iPod Integration Kit, Lighted Shifter, Two Tone Beige/Black Seats Trim, Angel Eyes Lights, Fog Lights, License Plate Lights, Caliper Covers, Wind Screen.
Next Mod- Lighted Door Sill (light Tape)