Not casually!
Pro Audio gear is generally designed to be mounted in a rack without any clearance above or below, or on either side! Accordingly, air flow is required from front to back and the fan is usually strategically located.
In the case of the QSC, there is essentially a tunnel/tube with heat-sink fins projecting into it that runs from front to back. The only vents are in the front and a circular hole in the back that is fit to the fan blades! So, unless you can adapt an efficient way to draw air through that tunnel, you can forget it!
I'm sure flow and cooling analyses are done to insure the system reliably cools even for a band playing outside on 100+ degree hot day!
Of course, this also makes it hard to come up with a one-size-fits all face plate, and even if for a specific model, you will have to provide adequate venting (which isn't often attractive) in the correct location(s) on the face.
I always thought the older Yamaha pro audio amp was a pretty good looking amp, however, they still won't match other gear. They do have removable ears for rack mounting, but I believe the handles are permanent:
Interestingly, I'm not a fan of their newer design, but beauty is subjective: