There may be a way to do that, however the reason it defaults back to the antenna is due to the fact that the tuner is the "always on" connection in the television. It's the one input that's powered by the television itself.
You can experiment by turning off Anynet+ in both the television and the HT system to see if the televisions will turn on to the previously connected input, however you'll lose the inter-connectivity of Anynet+ (such as the TV powers on and goes to the right input when the HT system is powered on). In some cases, people have posted that they've found this to be the best solution for them.
I have a Samsung LCD TV, LN52B630, connected to a Samsung Blu-Ray Home Theater system, HT-BD1250T. When I turn off the Blu-Ray system, the television source automatically changes to Antenna. This yields static because I do not use the antenna input. A cable from my cable box connects to an HDMI input.
Is there a way I can change the source that television defaults to? I would like the TV to default to the HDMI connection.