Creating headphone jack from speaker out

[r47]

I'm trying to add a bluetooth transmitter to my motorcycle stereo so that I can receive bluetooth audio in my helmet.

My current plan is to convert the powered rear speaker out into a suitable 3.5mm female headphone jack. The stereo manual claims speakers connected to the rear speaker out should have input impedance of 10 kOhm and an ouput signal level of <=1 V effective.

Do I need to worry about an impedance imbalance? I've researched this topic and did find the often-cited Rod Elliott article here Headphone Adaptor for Power Amplifiers

I'm not sure if a small amp like mine would still require such an approach. I appreciate you sharing your thoughts and experience.

[rjm]

A "powered rear speaker out" is a line level output, so you can just connect it directly to the bluetooth transmitter, or a headphone amplifier for example.