[sdiy] OT question about interfacing (impedance mismatch?)

[John Mahoney]

A friend called to ask me a question that I'm unable to help with. 
(Surprise! Not. ;-)

He has connected his old iMac G4 (with the dome base and chrome 
monitor arm) to his home stereo, and the volume is annoyingly low. 
Yes, the volume in the OS control panel is at maximum. Yes, different 
cables have been tested.

Not sure if this matters, but the iMac's "headphone / line output" 
has a source impedance of 44 ohms. We don't know the input impedance 
of the stereo's CD inputs, but surely it's nothing unusual.

Does anyone know what the problem is and how it can be addressed? 
Could this be caused by the CD inputs having impedance that's too 
high? [Insert "too high" joke here.] An additional preamp could be 
used, but that's a last resort workaround. How about a direct box?

Signed,
Mystified in Miami