Have you tried moving the Sony S300 to the 990 directly and letting the HD-A2 and DVD changer share the external switch? The HD-A2's HDCP handshaking with my TV has been pretty well behaved (takes a couple seconds after both the 990 and the MonoPrice switch get set correctly, but then it holds fine). The S300, on the other hand, I haven't tried and don't know if it'd work as well. If the HD-A2 is losing video also, of course, then this notion goes out the window...