Looks good, congrats on completing this.
If I were you, I would probably find a solution for holding down your internals. It'll make moving the cabinet around a bit easier if things like the PC, Woofer, and volume control is all battened down.
I hear you on the weight. And thank you for mentioning that. I've been trying to explain the weight factor in another member's project thread here, someone doing a pretty overkill 2x4 framing before even adding the cut panels, but it seems like they're going to learn the hard way.
You didn't put in that overkill framing, and opted for a regular assembly, which I commend you on. Even then, the weight is pretty hefty with the monitors and gear in it, so I'm happy to see you didn't do overkill too much on the wood. I mean, you got a bunch of support braces, and I guess the additional keyboard shelf would add even more weight, but at least you didn't frame it like you're building a house.