I bought a Schuberth C3 helmet and the SRC comm system looking to connect to my Zumo (Road Tech) 665. The helmet fits like a glove. With the SRC collar and the mike there's a lot crammed in there. Took a 3 hour ride yesterday, and didn't notice all the gear after awhile. Per the manual, I connect my iPhone to the Zumo and the Zumo to the SRC. The GPS, phone and XM work ok.
XM volume was low. There's a recently released Garmin fix that enhances Bluetooth volume for audio and allows separate control for GPS volume. Fixed the issue. (Note that you must also tinker with speaker placement in the helment to find correct ear alignment.)
The connection between the 665 and the SRC occasionally breaks and a manual reconnect in the 665 Bluetooth screen is required. Also, SRC manual says I should be able to connect via Bluetooth an MP3 player AND separately connect a phone through the 665. So, I connected my Blackberry to the 665 and my iPhone to the SRC, hoping to stream Pandora through the SRC. It works but causes problems with the 665 mentioned above. Reached out to Garmin and Schuberth support and will update after I hear. Some posts on the Zumo forum site seem to say it can't be done, but SRC manual seems to say otherwise.
I'm Impressed with the helmet and the SRC design. Typical setup snafus. Not a complaint. It'll give me the basics (GPS, XM and phone) but I'm working at more (Pandora stream).