How about having dedicated thread headings for example Denon, Pioneer, Sony Etc. So on the home cinema page have threads that relate to a make or question, HDMI is very popular so instead of starting a new thread just click on HDMI or if you have a qeustion about a sony product click on the Sony thread, again this would avoid new threads about Sony, and so on. This seems to work well on other well known forums, and can help viewers go straight to that topic or question, i know this would need changing via the website by your designer, but might not be as difficult as it sounds, anyway just a thought.