Mats,
in order to hear the radio audio, you must have full control of the radio, to turn it on and properly set the audio gain. Is the IC-706 properly interfaced to the RRC Radio Box ? Does your set up works fine when you connect the radio with the RRC Controller ?
I'm using a remote Kenwood TS-480 with RRC 1274A and RRC CLient 1.3.1 + Ham Radio Deluxe in SSB with good results. Audio is excellent in both directions.
I'm still having some problem on CW and basically I don't like HRD, but the client works well.
I'll be happy if I can help.
73 Enrico
I4GAD