Hi, sorry for the delay in my response. I use a spectrum analyser in my DAW while mixing. I’m sure you’re talking about a standalone spectrum analyser. I use a plug-in.
Good question, I'm using the x4 because of the size. I want something I can use as a controller for my monitors and other studio stuff. The X4 controls everything, it would have been difficult to have the rack mount version so close to me on tbe desk.