The VX works perfectly with the 30-pin connector cable delivered with the Sonic Port (non VX).
I only had issues with the Mobile Pod app on my ipad 3. Under iOS 7.0.6 there is no Mobile Pod version working with the VX device, you have to use iOS 7.1 as a minimum. The update to iOS 7.1.2 wasn't too easy with iOS 8.0 already active on air. It's a matter of rebuilding the device with a downloaded ipsw-file, not to forget the time consuming backup and restore of all apps and data. But finally everything ist working like a charm.
Thanks for your support!