As I continue to use the TVHeadend and XBMC setup I'm starting to find the odd little problem crop up. Most of these are pretty minor and can fix them as I go along (Pause live TV still a major missing element to this, and not one that looks like it'll be sorted soon unfortunately). One such minor issue I found was when setting up hardware adapters that can provide the same channels.
I have two DVB-S cards (Satellite, from my original quad-LNB) and one DVB-T (Terrestrial from the aerial installed in my loft). Now for whatever reason the DVB-S signal/channels show up as much better quality than the DVB-T (Not knowing the technologies, this may be expected due to available bandwidth on the MUXES, or whatever). So if I tune to BBC1 on my DVB-T its worse quality than on the DVB-S. The problem is that the DVB-T card seems to give out a signal quality of 100% all of the time, and the DVB-S can vary depending on weather conditions, etc. So TVHeadend was wanting to use the DVB-T card, and hence we got worse quality pictures.
I noticed in the TVHeadend issue tracker a request to be able to prioritise tuners, which sounds ideal. Basically in a nutshell somebody has modified the code so that you can force in a priority, to add "distance" (Using cisco/network terminology) to the adapter, and so make it less preferable for tuning. Martin Mrvka kindly produced the patch for his code modification so I could download and test it, and so far it looks good.
I've added a distance of 50 to my DVB-T card, and left everything else on defaults. So far it looks to have worked, however I've not fully tested it, so will do so over the next couple of days and see how it goes. Anyone else interested in this can get the patch from: https://www.lonelycoder.com/redmine/issues/343
Don't forget to post back and let him/me know how the patch works, see if it does the job for you too!