They don’t have an issue out yet (it’s coming soon) but they do have a page at Brill, so it must be official. Here’s the description from that page:
Greek and Roman Musical Studies is a new journal, the first specialist periodical in the fields of ancient Greek and Roman music. It will publish papers offering cultural, historical, theoretical, archaeological, iconographical and other perspectives on music in Classical antiquity, and on its reception in later times (especially the Middle Ages and the Renaissance, but also more recent periods). The Editorial Board will also consider contributions on music elsewhere in the Mediterranean region, including Egypt, Syria, Palestine and Mesopotamia. Cross-disciplinary approaches will be particularly appreciated.