After Susquehanna assumed full ownership, KFME flipped to adult hits, and rebranded as "105.1 Jack FM", on October 7, 2004, at Noon.

Like other Jack stations, KCJK was mostly jockless and stuck to a computerized playlist, highlighted by segments that include the “No-Request Nooner” and liners chastising drivers who slow down to see accidents in the opposite set of freeway lanes.

Upon taking over the station, Cumulus added live disc jockeys, a rare move for an adult hits outlet.

On June 15, 2016, at 7:30 a.m., after playing a block of "end"-themed songs (including "Enjoy the Silence" by Depeche Mode, "In the End" by Linkin Park, "Should I Stay or Should I Go" by The Clash, "Come Sail Away" by Styx, and "Closing Time" by Semisonic, which then culminated with "The Final Countdown" by Europe), KCJK swapped formats with K273BZ/KCMO-FM-HD2, adopted their alternative rock format, and rebranded as "X 105.1."

[7] On October 10, 2019, at Midnight, after playing "Helena" by My Chemical Romance, KCJK relaunched as 105.1 The X, shifting toward a hybrid format with an active rock-leaning presentation that continued to feature an emphasis on alternative rock content alongside other hard rock hits (dubbed "rockternative", with examples spanning from Disturbed, AC/DC and Mötley Crüe, to Pearl Jam, Tool and Panic!

[8] The station continued to air the syndicated Woody Show in morning drive, while other dayparts were held by local DJs.