If you're looking for something besides Mix Check Studio, there are plenty of AI-powered audio mastering services you can try.
Cryo Mix is a full-featured suite of tools to improve audio, including AI Mixing and Mastering. You can upload instrumental and vocal tracks, tweak settings, and extract stems like vocals and drums from a single audio file. It's also got a user-friendly interface to let anyone get good-sounding audio, not just audio pros.
Another top contender is eMastered, an AI-based online audio mastering service that can deliver fast, professionally sounding results. It's got an intuitive interface for uploading tracks and getting mastering results immediately. Stemify lets you get high-quality stems for vocals, drums and other elements, so you can make instrumentals or a cappellas, and the service offers free and paid accounts.
If you want a tool that can master audio with a text prompt, the Diktatorial Suite is worth a look. It can optimize for streaming and offers different genre settings. The suite is designed to protect your files while you're uploading and uses advanced features like stereo width and analog warmth for more professional-sounding audio.