I currently have two Ceton InfiniTV4, two ATI DCT, three HDHomeRuns, an AVerMedia Duet, an AVerMedia AVerTV USB HD PVR and a Hauppauge HD-PVR connected to my primary HTPC [i]for testing[/i] and have not seen any conflicts between them.
The only time I’ve had issues with pixelation andor freezing is when I tested lower quality op-amps and passive splitters.
When you had issues did you go into the tuner debug screen (4-1-1) to see what tuner was having issues?
Update: Forgot about the two ATI DCTs…