Trippy discussion.
I'm just now building a tabletop over a 1/3 section of a huge corner desk. The original carcase is 24" x 48".
I wanted my audio mons higher, first was thinking 6"--- leaves enough space for CD's under the riser.

Scrap from cutting out the riser left me the option to go up 9" overall, so I went for it. The video monitor is A LOT higher than I am used to. But I like it that my audio mons are very near ear-height now. Plus, I made the desktop big enough (72" w x 38" d) to hold a U-20 keyboard, 1402 mixer, and best of all my Klipsch 2.2's!!! I had to build a pair of legs to go under the very back of the setup 'cause it was a little shakey. It's rock-solid now.
Still needs some finishing touches. I made the top from a piece of shop birch I had been using for a workbench, and an 18" x 96" rip of another sheet of birch shop ply. So I'm less than $75 materials so far. I'm thinking about getting some 2" Panduit across the back to put speaker cables into, and a little trough for audio cables behind the Mackie.