Hello Lewis,
If you have read any posts on this subject you will see that the auxillary input/output needs to be about 500 to 600 mv as an input. we used to use hifi separates such as tape players or cd units which had an output in this range. The mute plug needs to be out or you build a switching circuit to bring the mute back into play when a record is selected.
Regards
Alan
Alan Hood
ami-man
UK