About 3 years ago I bought a couple of Parrot CK3100 Bluetooth units. One was installed in my (at the time) MFL CD Estate, the other in SWMBO's Mk 1.5 Focus.
The Omega install used the "line out" and mute to connect to the mono audio input (as used by traffic master), this continues to work well even though the car is no longer in my ownership.
The Focus install used an adaptor from Parrot to switch the speakers over to the Bluetooth control module when in use. All was well until a few weeks ago when SWMBO reported distorted music. I investigated and true enough, there was distorted sound from the drivers door speaker. Now, her music taste is for loud rock, so I assumed that she had blown the speaker. So, I fitted another one (from a breaker) and it made no difference. I then swapped the head unit - although a Ford unit, it's quite a rare one only being fitted as an option to some models - hence finding one wasn't easy. Find one I did and fitted it. It made no difference, grrrrrrr.
So, speaker replaced, head replaced - that only leaves the wiring. DOH - and the Parrot. Removed the Parrot and the problem has gone. To say I was peeved was somewhat of an understatement. I guess they have used cheap and nasty changeover relays, one of which has gone flaky after 3 years use.
So, be warned guys. IF you use a Parrot AND switch the speakers using their own plug & play adaptor then you may suffer the same problem I had. The line out install continues to work perfectly.
I will report this to them, but suspect they really won't be interested given that its well out of warranty. Smack of poor design IMHO. Hey ho.
I hope this helps someone.
Rob