Digital Audio Workstations (DAWs) are central to modern music production but often encumber the musician's workflow, tethering them to a desk and hindering natural interaction with their instrument. Furthermore, effective remote collaboration remains a significant challenge, with existing solutions hampered by network latency and asynchronous file sharing. This paper investigates the potential of Mixed Reality (MR) to overcome these barriers, creating an intuitive environment for real-time, remote musical collaboration. We employ qualitative and speculative design techniques to better understand: 1) how players currently use DAWs, and 2) to imagine a speculative future of collaborative MR-DAWs. To facilitate this discussion, we developed and evaluated the usability of a design probe, MR-DAW. An MR system enabling multiple, geographically dispersed users to control a single, shared DAW instance while moving freely in their local spaces. Our networked system enables each remote musician to use a physical foot pedal for collaborative looping, merging a familiar, hands-free interaction with a shared virtual session. Based on interviews and system evaluations with 20 musicians, we analyze current practices, report on the user experience with our MR system, and speculate on the future of musical collaboration in MR. Our results highlight the affordances of MR for unencumbered musical interaction and provide a speculative outlook on the future of remote collaborative DAWs in the Musical Metaverse.