from what i gather, rs232 is the most reliable method of controlling the monoprice 4x4 matrix. currently, the xp-6 is connected from an mpio to the matrix via infrared emmiter. the system was installed by another tech and system file that are no longer available. my client is having issues with intermittent signal loss to one of two flat screens (outputs A&B) from input 1 which is a comcast motorola cable box. the output A is run with an HDMI cable and the output B is run using the cat5e/6 to a monoprice reciever. seems to work fine for a short time after disconnecting power to the matrix, only to be called back for loss of signal to one or both flat screens. the remote is a mini ipad with the rti panel. thanks in advance for any assistance you may be able to provide.