So, I have had a lot of problems with my stack, which I've found out here is caused by mixing a 15 with a 410.
I use gk backline gear. I have a chance to get a gk 410glx for cheap. Could I use that and the backline 410 or am I just looking at more problems? I could just go buy another backline 410
You could, and it may work, but the problem with mixing cabs is you never know until you try it since it's very unpredictable, while matching cabs are a sure thing.
I own a backline 410 and had a chance to run it with a 410 GLX.
For me it didn't work. The two cabs sound completely different and sounded really funky together. (Funky in a bad way)
Now there were a couple of things happening at the same time here...one I was playing in a room I had never played in before, and it had some weird acoustics and two I only got to try it out that one time.
If you get a chance to try them out together I would strongly advise it so you know for sure. It didn't work for me, but it may for you.