The speaker protection i have uses 2 relays for stereo channel (1 relay for each channel). But I'm thinking of using it in "mono-mode"  and shorting the R+L input and R+L output to make it more "robust". Will that work?

(this would mean I would need 2 devices for 2 channels.)

Thanks again

You can’t control the ganged mechanical contacts to open or close at the exact same moment. So technically when two or more contacts are connected in parallel, the interrupting current rating won’t double. However, paralleling the contacts does reduce the contact resistance, if that’s your goal.

Alternatively https://neurochrome.com/products/guardian-86