Its an HD DVR & an HD channel contains capacity of 5 sd channels. If an user want to record two HD channels at same time may be 1 cable not enough to carry 10 times sd channel. That may be reason. And you mention about splitter, ordinary splitter is not work properly. It only support 1 input at a time. Which work with TS maybe it is multi switch equipment & in DVR maybe is not enough like cable which I mentioned above.Signal loss is main reason.