I've played many times in similar situations, and until I began using the Bose L1, I experienced the same problem. I played a 50th wedding anniversary at a huge, upscale country club on Maryland's Eastern Shore, the ballroom was where I was set up, and around the corner in another room was the dining room. The system covered the entire venue with very little falloff, and even I was amazed.

The first time I encountered the Bose L1 system was when Uncle Dave was playing at an Italian Restaurant in Philadelphia, a venue that consisted of a bar in the center room and dining rooms on each side of the bar section. There was a partial wall between each of the rooms, with about a 4-foot vertical opening between the rooms with spindles on the walls, and lots of hanging, artificial plants. No matter where I walked throughout the entire complex, the music volume was nearly identical There was virtually no falloff in any of the rooms. And, while Dave was playing and singing at a relatively modest volume, everyone could hear him just fine. Ironically, the couple that was sitting just 6 feet in front of the sound system were holding a conversation in normal tones and they had no trouble hearing each other. That sold me right away on the Bose system.

Knowing that you wish to remain in stereo, I believe that it would be ridiculously expensive to purchase a pair of standard L1 systems in Germany just to retain that stereo sound. And, stereo would not be transmitted to the adjoining rooms. However, I can assure you that a pair of Standard L1 Bose systems would provide the most incredible sound you'll ever hear, even in the adjoining rooms.

Your only other option is to go with powered monitors in the adjoining rooms, run long cables to them from the line out of your existing sound system and hope for the best. From my own, personal experience, the audiences do not care if the sound is mono or stereo. The player is the person that seems to benefit most from stereo - not the audience.

Good luck,

Gary