Klaus,
When I ordered My adapter from soundgate (PIOGMV2) they told me I could us the PIO/P-RCA adapter to conect any additional device through the xm 910 tuner. Is there a difference between that and the Pioneer CD-RB10 you have posted here?
Check this out and tell me what your think.
http://store.yahoo.com/logjam/piepioprca.html