I also have a premium Spotify account @ $9.99/month. Now I probably listen to more music than most people, as I assume other premium subscribers do. Doing a back of the napkin calculation I listen to an average of 30 songs per day, so maybe 900 plays a month so you could say Spotify charge me $0.01/play. 40% payout isn't bad, maybe it should be 50% or 75%, who knows what Spotify's infrastructure costs them. Either way in the old days (> ten years ago) artists were getting no where near 40%.
I've only bought two albums this year, Boards of Canada and Flying Lotus, they were both not immediately on Spotify. This is probably the best course. Release on MP3, CD, Vinyl, for the first couple of months for the hardcore fans then release to the streamers.
The OP probably has his record label still taking a huge chunk of his payout. Cut out the middle man, self publish. Streaming is only going to grow, streaming profit will eventually go up.
Self-plug! @spotify http://open.spotify.com/album/2ASb9HnDamAwrsJQ9gKtqp @soundcloud https://soundcloud.com/kreek