I have a directv 4 room system and each room has HD. I want to get the DVR for the den, but I don't want to run another coax down the wall. Can I connect a multi switch to the single lead in the den from the dish and run two from the switch to each tuner on the DVR?
No, a multi-switch is a switch, not a splitter. At best (if it worked), you would only receiver half of your stations. The receiver will output a 13 or 18 volt signal to select which LNB it wishes to use, the multi-switch then sends the signal from the correct LNB to that receiver. With only one satellite signal in, half the time the receiver would select the other LNB which is open and have no signal. But it would probably not work at all, since the input of the second multi-switch would most likley not pass a 13 or 18 volt switch signal upstream to the first multi-switch. So the first multi-switch would not output anything at all on that line.