I have an old Sony MHC-2600Mini Hi-FI bookshelf system with only wired speaker outputs. Can I hook up a bluetooth transmitter

Solution
If you have RCA outputs labeled record out then you need a cable with 2 RCA at one end and a stereo mini plug at the other. This output is fixed and will not be affected by the volume of the Sony.
If you only have speaker outs then you can connect a speaker to line level adapter like this onehttp://www.crutchfield.com/p_142LOC80/Scosche-LOC80.html
to the speaker outs and use the same cable above. This output will vary with the volume of the Sony. You can use a speaker selector to choose either or both the speakers and transmitter.
If you have RCA outputs labeled record out then you need a cable with 2 RCA at one end and a stereo mini plug at the other. This output is fixed and will not be affected by the volume of the Sony.
If you only have speaker outs then you can connect a speaker to line level adapter like this onehttp://www.crutchfield.com/p_142LOC80/Scosche-LOC80.html
to the speaker outs and use the same cable above. This output will vary with the volume of the Sony. You can use a speaker selector to choose either or both the speakers and transmitter.
 
Solution