My 2007 xc70 had no (FL) or distorted (FR),sound coming from the front (F)speakers. This is the situation regardless of input selection. I had all the speakers replaced on advice from a car stereo shop. This did not correct the problem.
I bought a used HU 650 radio from Discount OEM radios installed it and this did not solve the sound problem. Yes, it may be another screwed up radio I'm thinking something else.
I have read that the HU 850 does require an external amplifier. Could my car with the HU 650 possibly have an external amplifier also? If so, where would it be located? Does anyone out there have any insight as to whats going on with this situation or dealt with it themselves? Thanks for your help.

 

Your car should be equipped with an external amplifier. If so, it would be located under the passenger front seat. Since you've already addressed the speakers and the control head, the amp would be next. Failing that, it could be a short somewhere in the wiring harness system.

 

I have looked under my passenger seat and can not seem to identify the amplifier. Can you give more precise location or shape of unit?
Thanks