Lopark,

You can certainly use your DT50 combo speakers with another amp or head. I use my SV212 (combo) twin 12 speakers on occasion as an extension cab for my DT25 head/cab. The 2 x 12's from the SV are a total of 8 ohms (unlike your DT50's) and my DT Cab is 1 x 8 ohm, I need to plug them BOTH into the 4 ohm sockets when using them together. If (for example), I was JUST using the 2 x 12 SV Cab alone, then it would go into the 8 ohm socket on the DT25. You are right, with JUST your DT50 speakers acting as the sole cab, you would plug them into the 16 ohm socket on your Orange amp. You will need a female to female 1/4 inch adaptor on the speaker plug of your DT50 so you can extend it long enough (with a regular 1/4" speaker cable) to reach your other head. I would think that it would not be long enough otherwise? That's what I had to do with my SV212 speaker cable/plug. It was too short to go anywhere except the SV speaker socket.

Firmware updates ONLY affect the amp. The speakers are passive devices, they have no firmware.

Hope this helps.