Mac Miller performs on stage at Shepherds Bush Empire on September 1, 2011 in London, United Kingdom.
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Mac Miller ft. Diggy: "Definition of Cool"
The 20-year-old Pittsburgh MC teams up with Rev. Run’s 16-year-old rapper son Diggy (who puts on an aristocratic British affectation for this track à la Nicki Minaj) on a surprisingly effective collab over a warm, funky groove. 

Burial & Four Tet: “Nova”
Electronic maestro Four Tet and lauded dubstep dude Burial released a new collaborative song, the six-minute “Nova” which you can stream right here.

Jonny Greenwood & Krzysztof Penderecki: Krzysztof Penderecki And Jonny Greenwood
The collaborative album between Radiohead guitarist Greenwood and avant-garde classical composer Penderecki is excellent and unsettling. This is a big day for university music majors. [NPR]

Tanlines: Mixed Emotions
The debut album from the tantalizing Brooklyn dance duo is online for your pleasure. [NPR]

Simian Mobile Disco: “Seraphim”
The first official single from the electro house duo’s upcoming album. [Stereogum]

Rick Ross, Wale & Meek Mill ft. T-Pain: “Bag of Money”
An unfinished version of this song hit the 'Net a couple of months ago, but this is the real deal. [XXL]

Neon Indian: “Hex Girlfriend (Twin Shadow Remix)”
A Record Store Day release come early. [Prefix]