Series 1 - 45 2x12 plus a 16ohm Marshall Cab?

[JED]

Hi folks,

Bought the HT-5 in August and loved it so much that I just went out and bought a Series 1-45 for larger gigs. Awesome piece of gear! Now my question:

I also have a Marshall 1960 TV 16ohm cabinet. Wondering if I can use this cabinet along with the internal speakers in the combo (both at the same time) or do I need to disconnect the internal speakers when running it through the Marshall 16ohm 4x12 cab?

Dumb question, but I really don't want to do any damage.... : )

Cheers,