Unsurprisingly, Rhapsody has announced that it is ending its partnership with The Echo Nest, the Cambridge-based data think-tank acquired by Spotify earlier this month. It's the second Echo Nest partner, after Rdio a couple weeks ago, to end a partnership with The Echo Nest.

Algorithms, the math engines which power music recommendations on services from Facebook to Netflix to Rhapsody, are at the center of an ongoing public debate about the promise -- and problems -- they bring to tech-based businesses. Reading into users' behavior to bring them exactly what they'll enjoy, keeping them on a particular service for as long as possible, will be a winning factor in the ongoing streaming 'war.'

"We have never been completely satisfied with recommendations from any third party," wrote chief product officer and SVP of the Americas Paul Springer in a statement. While it may be the case that Rhapsody only trusts its own users' usage data, the data that The Echo Nest, or an internal Rhapsody team, analyzes is based on practically the same catalog of 30+ million songs that Spotify uses. What that means is that the conclusions and recommendations data scientists reach would likely be very similar across platforms at large scales.

Rhapsody would not elaborate further on the decision.

Rhapsody is the no. 2 music streaming subscription service, with revenue of $206.1 million (down $52.6 million from 2012) and an operating loss of $70.8M in 2013, according to the company's SEC filings. The service is active in 32 countries, 23 less than principal rival Spotify.