Your idea has too many masters to please. It's for the industry, but it's also for the artist. It presumably enables the artist to accomplish something with their fans/customers. So, it's for them, too. Pick one problem and solve it.
Don't bother trying to solve a problem for the big 3. They have only one goal when it comes to investing in tech companies: extract as large an up-front licensing fee as possible before the company runs out of cash. Consequently, they're looking for companies with a fresh seed or series A or B round whose business model absolutely relies on licensing their IP.
They are not interested in placing a bet on anything else. I know because I wasted a lot of time pitching to them (Sony, UMG, WMG).
You'll do much better focusing on solving a problem for the artist that doesn't make them replicate what they're already doing. In other words, you don't want to be YET ANOTHER middle man. Yet another platform for them to have to play on. They won't join unless you have massive, paying fanbase, which you don't ... or you can SHOW that your platform more accurately, intelligently, or otherwise successfully connects the artist with the specific people they want or need to reach.
That's a tall order, and like any platform play, it suffers from the chicken and egg question. How do you get a valuable group of users (fans), without the artists on board? And how do you get the artists on board without the fans? Simply setting up tools, favorable monetization structures and architectures won't be enough to attract either side.
But you asked about successfully pitching the idea. Short of building test version that can validate your assumptions, you could devise an architecture and set of rules (algorithms) that in some way makes artists more successful. If it comes across as plausible, you might be able to successfully pitch that. For example, you could say your system is more efficient, pulling together artist data and media from Bandzoogle, Reverbnation, Sonicbids, iTunes, Tidal, CDBaby, etc., and compiling it with their own social media accounts, event calendars, merch sales, etc., to produce a single dashboard that ... what? That's the key. In what way does it make the artists' lives better? Remember, they have almost zero incentive to try something new, untested, without an audience, even with "good" terms. Why? Because the amount of work required to set up on the new system isn't worth the risk. Unless you make it obvious that it is.
If you are able to create such an app idea, or place (even "on paper"), investors will want to know why you, personally, and your team are the best people to actually make it happen. If you can hit that note, too, then they'll want to know why you won't be made irrelevant if company X decides to simply add features you propose to their already vibrant businesses. Lastly, if you can convincingly and compellingly answer those questions, they'll want to know how much it costs, how long it will take, and how they will make their money back.
First, though - pick just one master to serve, and make it all about them. Doesn't matter if it's artists, fans, industry promotions folks—as long as it's clear your idea will make their jobs better (easier, cheaper, faster, more profitable). Ancillary opportunities can be glommed onto that core product later, if you succeed, but without focus, you risk appearing as a bad investment.
