OK. Went back to the Pinnacle Pro Stick. Installed Pinnacle TVCenter Pro (previously I had just installed the driver). This added a variety of Pinnacle codecs and decoders to my system. Once these were installed, MC played the audio with no problem and no special configuration.
In addition, the sound now works on the AVerMedia card. Interesting thing is that I have it set for the same audio and video decoders as I was using before when there wasn't any sound.
BTW - I had to go to the Hauppauge ftp site (not the regular download site) to get the latest version of TVCenter Pro, which is compatible with Windows 7 64-bit machines.
Thanks for the help.
S