I'm looking at the HT-5. Now I belive th Kustom Dart Cab I have is solid state, can the HT-5 plug into it without any problems? I belive the cab is called the Kustom 66 dart. It the tuck and roll style with red exterior.
A cab is just a speaker in a box with a wire connecting it to a socket.

It's the impedance of the cab and amp that you need to worry about.