My SMH10 received intercom audio becomes unintelligible greater than 50', they say my xmit audio is fine.

The received audio from other paired users sounds raspy like listening through a torn 2" speaker. When they are within 10 to 20 feet they sound clear.

I've swapped the main unit with other users and no change...is there any circuitry in the base/clamp unit? The speakers seem fine. I've even enclosed the speakers in a thin layer of foam and no help.

There is no other bluetooth-activated equipment on the bike at the time, however when I do activate the bluetooth on the Garmin Zumo550 GPS mp3's, the music audio is fine...quite good actually.