Jim,
Here are the details.
1. Installed the VAISTech SLU to give me the Aux In port. This used an inline harness that plugged straigt into the head unit, with the other end connecting to the original Lexus harness. that worked great. No issues.
2. Installed the Parrot 3100 Bluetooth kit. Purchased a quick connect harness with that. That harness plugged into the original Lexus harness just like the SLU, so they are now daisy chained. I am certainly wondering if that is the problem.
3. I currently am using a separate speaker (sitting in my back seat) for the Parrot. I ran wires into the trunk from the Parrot harness that I will eventually splice into the door speaker wires going into the amp, but for now did not touch the original speaker wiring as I wanted to get everything else working first, hence the speaker in the back seat.
4. The radio muting came as part of the Parrot harness I bought. Therefore it is hitting the mute line going into the head unit.
I think that's about it. Without some further advice from anyone I plan to disassemble the center console again and try all possible combinations of Head Unit, Bluetooth and SLU to see if the volume only freezes in certain configurations.
Joe