A variety of “DJ only” services, but all music is purchased legally. Not only is this a moral issue, but the song is directly from the studio. When played on a high caliber sound system the difference in recording qualities is astonishing.
Some people “stream” their music from various services. Not only are they relying on the venues wifi – they are putting the music to your event in jeopardy. Internet glitches, commercials in the middle of music, dead air, and worst of all – bad sound quality.
All my music is on my hard drive. Reliable, glitch free, and great “from the studio” sound quality. Shame on the rest of you!