The station had a smooth jazzformat from its inception in December 2004 until August 2012, first as Couleur Jazz before being re-branded as Planète Jazz 91,9 in the summer of 2008.
On January 13, 2012, RNC Media applied to the CRTC to amend its licence conditions to allow 50% of its programming to be spoken-word and talk programming, with the remainder being its existing smooth jazz format (though its license also includes other forms of jazz) as well as blues and other special interest music genres; its application hinted that the station would take a direction more towards its Quebec City sister station, CHOI-FM.
Logo as CHOI Radio X Montreal, 2012-2014.
On August 20, 2012 at 5:30AM, CKLX-FM flipped to the new CHOI Radio X format, sharing the branding with its sister station, CHOI-FM. Currently, half its schedule is spoken-word talk radio programming, with weekend's Le GarageRock program. Smooth jazz will remain on the schedule temporarily during the evening and weekend morning hours when it is still announcing itself on air as Jazz 91,9, though not on the website. All this is pursuant to its CRTC license, in which 70% of its music programming must be jazz or blues. The hybrid format remained in effect pending its approval to allow a mainly-spoken-word format. The station's first effort to gain approval was denied by the CRTC on March 14, 2013. On April 8, 2014, the CRTC approved CKLX's request to discard its music requirements as part of its license renewal, in exchange for a requirement to carry a minimum of 50% spoken word and talk programming. While CKLX's new license takes effect on September 1, 2014, the format change goes into effect immediately. On September 9, 2014, the station was rebranded as Radio 9. The programming has also been changed and some different hosts have joined Radio 9, including Louis Lemieux, previously from Ici RDI.