Eleven Rack producing little to no signal through Behringer power amp

[Decosboss]

Hey,

New 11R owner, recently purchased a secondhand unit, had no issues with it, but only ever played through headphones until recently. Purchased a Behringer A500 power amp (https://static.bhphotovideo.com/lit_files/84866.pdf) to run through my Marshall MX212 cab (https://marshall.com/marshall-amps/p...212-and-mx212a).

My chain is as follows:
11R Out to Amp 2 > A500 Input 1 > A500 Bridged Mono Out (note: I have same issue in stereo mode) > Marshall MX212

All settings on the 11R seem correct, but maybe I'm missing something? When wired up as described above I get a very weak signal, and I start to get popping noises when I turn the channel volume of the A500 around 12 o'clock.

I can't think of any reason for this to occur, I've tried various alternative methods for troubleshooting, but with no success. If anyone could point me in the right direction, or tell me what (if anything) is faulty, that would be much appreciated!