Guys, I have a 6505 head, a line 6 head, and a 1936 marshall cab (2x12).

is it safe to run each head thru the 2 cab inputs at the same time?

Here are some of the specs my gear has:

Cab: 16 ohms stereo 75watts per channel
Line6: 4 ohms minimum
6505: 16 ohms, 120 watts.