I have an older Motorola PVR DCT3416 connected via HDMI to a Denon AVR 890 to an older Sony Bravia KDL-40Z4100. So basically all the equipment is about 6 - 10 years old.
In the last few weeks when Sportsnet switches to live broadcast I occasionally get no sound. Last night's Canucks game recording from CBC (simulcast on Sportsnet) was missing audio except for commercials and intermissions, earlier in the week a post game interview with Ryan Miller had no sound and quite often this week when they are playing highlights and switch to the in game announcers instead of the Sportsnet Central blabber-mouths then the audio also cuts out.
I don't see anyone else complaining about Sportsnet's audio but I can't believe this is hardware either. The other thing that has happened quite a bit for the past year on Sportsnet only is certain portions of the broadcast the sound is really quiet with occasionally bursts of regular volume. Kind of like when you have your headphones partially plugged in and you can only hear from one ear. No problems on any other channel.