I don't know which happened first, but some versions of the X7 (our name for that type of model) have been named Q7, you'll also find AC8350, EKB311 (and quite a few similar variations), B351_BT etc etc. We also have a model (that is like an X7, but with a webcam built in) that we call a Q7. Sorry for the confusion!
Regarding the lack of sound, just to double check, using the lead that your other (sound working) box normally has connected, plugged into the same TV, this device has no sound?
If this is the case, please send us another e-mail, and include in the message a request to refer your case to Chris (me).