There is now a machine that will listen to a song and tell you, with a number, how much the world is going to like it. Researchers at the AMAAI Lab at Singapore University of Technology and Design built it. It's called APEX, and it was trained on more than 211,000 AI-generated songs, roughly 10,000 hours of audio pulled from Suno and Udio, to jointly predict two things: raw popularity, meaning streams and likes, and five separate dimensions of perceived aesthetic quality, pulled from frozen audio embeddings generated by a model called MERT. The uncomfortable finding buried in the paper is that the machine is far better at judging whether a song sounds good than at judging whether people will actually love it, and it does noticeably better on instrumental tracks than on anything with vocals, where taste gets messier and more human. In other words: AI can approximate craft. Chemistry with an audience is still slipperier. To be clear about what APEX actually is: it is not a consumer app and there is no website where a casual listener can drop in a song and get a score back. The AMAAI Lab released it as free, open source research code on GitHub and as a downloadable model on Hugging Face, the online hub where developers share machine learning models, under a permissive license that lets anyone use, copy, or build on it. Testing it requires some technical comfort. A user needs Python installed, along with a handful of machine learning libraries such as PyTorch, then downloads the pretrained model and points it at an audio file on their own computer. Feed it an MP3 and it returns a set of numbers: a predicted streams score, a predicted likes score, and five separate aesthetic ratings covering qualities like coherence, musicality, memorability, clarity, and naturalness. There is no button-and-slider interface built for musicians or fans, in other words, this is a tool made for other researchers and engineers to test and build on, not something a songwriter can open in a browser tab and use over coffee. That gap matters because the industry racing fastest toward answering it is Suno, the Cambridge, Massachusetts AI music company that has turned "type a prompt, get a song" into a business generating an estimated 7 million tracks a day. Suno already has a tool built for exactly the instinct to take something loved and build something adjacent to it. Its upload-and-cover feature lets a user drop in an existing audio file, one they're required to confirm they own the rights to, and rewrite it in a new style while the underlying melody survives the transformation. Feed it a stripped-down piano ballad and ask for djent, or a folk tune and ask for Afrobeat, and the skeleton of the original holds while the skin changes completely. It is, functionally, a machine for zeroing in on whatever made a song click and rebuilding a new one around that same spine. Suno just wrapped that capability, and a lot more, into v6, a family of three new models launched on September 9. The flagship v6, an experimental v6-wild, and a free v6-mini are the company's first models trained from scratch on catalog it actually licensed, from Warner Music Group, BMG, and independent distributor Believe. Warner signed its deal back on November 25, 2025, ending the copyright suit it had brought against Suno. BMG followed on August 12, 2026, covering both recordings and publishing. Believe and its TuneCore arm signed a day before launch. Suno's chief product officer told Bloomberg the company will now share a cut of revenue with those partners starting from launch day, with labels responsible for splitting that money among their own artists and songwriters going forward. Co-founder and chief executive Mikey Shulman framed it as vindication after eighteen months of being treated as the industry's most convenient villain. Suno has weathered a hacker leak alleging its models trained on scraped audio, an admission that it pulled data from YouTube, and a banner-towing plane reading "Say No To Suno" flown over an AI investor summit where Shulman was speaking. The company has also just raised $400 million at a $5.4 billion valuation, and by earlier this year had been used by more than 100 million people, with 2 million paying subscribers. None of that goodwill extends to Universal Music Group or Sony Music, who never signed licensing deals and instead filed a second lawsuit against Suno on September 18, a 45-page complaint in federal court in Boston that adds more than 60,000 specific recordings to their claims. Their argument is that training a supposedly clean new model on the outputs of an old, allegedly infringing one doesn't wash the infringement away, memorably calling v6 "the fruit of the same poisoned tree." Under US copyright law's cap of $150,000 per work for willful infringement, the theoretical maximum on the table now tops $9 billion. Suno also lost, decisively, in a Munich courtroom in July. Germany's music rights society GEMA sued over six specific compositions, including well-known tracks like Rasputin and Mambo No. 5, and the Munich District Court rejected Suno's fair use defense outright, ruling the company had actively operated the model rather than merely hosting neutral infrastructure, and ordering it to disclose the scale of its use and pay damages. The court's reasoning leaned on a blunt distinction: it may be fair use to copy from a book to write a review, but not to steal the book in order to make the copy. Put those threads together and the picture is of an industry racing in two directions at once. On one side, machine learning that can now score a track's aesthetic polish and predict, with real but limited accuracy, how an audience might respond. On the other, a tool that lets anyone take the song that scored well, or simply the song they personally love, and generate a close cousin of it in seconds. The technology for identifying what's loved and the technology for replicating it have arrived in the same product, at the same company, in the same month that two of the three biggest labels on earth decided to fight it in court rather than cash a check.