Avicii posts a photo to Instagram of his temporary studio space, or as he says in the caption, "#temporaryhomestudiomode." The white/gray midi controller he is using is the M-Audio Axiom Pro 61 Advanced 61 Key USB MIDI Controller. It can be identified by its rounded edges, contrast between the black sides and the white/gray body, and the button configuration. The keyboard has 5 octaves, which makes it the 61-key version. (photo posted May 2014)more
I never mastered this but it did what I needed it to do and you could change the MIDI channel from the panel. I found the operating system to be fairly deep but obtuse at times and things that I thought should be easy sometimes weren't. Overall though I enjoyed using this keyboard with both a DAW and external synth voices.