I've had one of these chairs forever. Its design is simple; a triangular cushion, a pneumatic cylinder to adjust height, and a 5-wheel base – no arms. No back. There are tons of saddle chairs on the market, including some that look more like actual saddles, but I like Humanscale's design. It doesn't look too weird, and since the cushion is symmetrical you can sit down any which way from any approach angle.
Most studios have big-ass executive office chairs in front of the mixer. I've never liked that. They're too big to roll around in comfortably or quickly, the chair back cuts you off from the other people in the room and blocks their view, and it's hard to play guitar in any chair with arms. Saddle seats solve all these problems. Mine is compact enough to roll under my mixer when I'm not seated. It also makes me sit "actively", using my core muscles, which one may or may not consider a feature. I've compensated by inventing novel ways to slouch.
After 14 years with my Humanscale Freedom, why write a review now? Because a few months ago it finally broke. The plastic seat base gave up and cracked, probably thanks to me constantly leaning down to reach effects pedals. As I was ordering an identical replacement, I noticed the 15-year warranty. Could it be? I called and sure enough my chair was covered, no questions asked. I sent some pictures of the damage and soon after I had replacement parts in hand. The design has changed since 2003 (!) so they had to replace about 75% of the chair. Now my chair is good as new and I'm a customer for life. Try getting that kind of support for your $6000 studio monitors!
Humanscale makes high-end ergonomic office gear, so their stuff isn't cheap. They offer a lot of fabric choices at different price points, along with different finish, cylinder, and caster options, but the base model isn't too expensive considering how well it lasts. I have the high cylinder and foot ring, since I find that I sit higher in these stools than I would in a normal chair. You might not want a control room full of these, but as an engineer's chair I think it's perfect.