They have been a fixture simulcast since 2003. In September 2003, WZRB 104.5 FM dropped Urban AC and became WNXX simulcasting KNXX 104.9 FM The X. They were an Alternative Rock powerhouse for Baton Rouge blanketing downtown and both the northern and southern suburbs. On January 4th 2010 at 1:00 PM that stopped. Someone is doubtlessly updating their Wikipedia entry right now.
KNXX plods on with Alt rock as the X as they have been for most of a decade. The story starts back in 2000. New Radco LLC sold 104.5 WBJJ to Guaranty Broadcasting Corporation. WBJJ used to be an eclectic Rhythmic Oldies station which sported odd dashes of zydeco, and blues with the calls WUXN. But WBJJ was pretty much standard Urban AC fare. Guaranty nixed Urban AC and went alternative rock. Many rags identified them as a "rock" station and this is absolutely not the case, not by playlist not by branding.
In 2003 the WNXX/KNXX simulcast began and it ran until just 2 days ago. The simulcast ended abruptly in the middle of a sing without any preamble or apology. After a 6 second interval of silence WNXX became an ESPN sports talker. The audio is below.