Is a 75ohm resistor on the output jacks normal?

[JayCobie]

I was poking around inside my old Carlsbro TC100 two-channel 100w EL34 amp and noticed that the output jacks have a 75ohm resistor permamently soldered from positive to negative.
The way it's set up is not so that it gets removed from the circuit if something is plugged into the output, it's just always there.
I haven't had any issues with the amp (besides the fact that it's a 100w amp and it's super loud, but I can't change that easily).

I know someone has poked around in this amplifier before so I don't know if it's a factory installation. It's not on the schematic that I have.
Here are pictures of the wiring, the impedance selector and the schematic of the amplifier:
https://imgur.com/a/fxdhy

Can someone tell me if this 75ohm resistor is normal or if it serves some specific purpose?
I'm very much considering removing that thing to see if it affects the sound at all.

Edit: first I thought it was a 10 ohm resistor but removing it and measuring it out of circuit, it measures 75ohms.
The resistor has no markings on it so I can't know if it's supposed to be a different spec resistor.

[sluckey]

It's just a protection resistor. It just may save your OT, output tubes, and sockets in the event that you try to play the amp with no speakers connected.