Although the station began broadcasting at 95.7 in 1995, it has its origins as a Class A station at 95.9 MHz known as KARL,, then KKOS. During this period the station had various formats, including adult contemporary, CHR, and AAA. However, an interference problem in Mexico ended up resulting in changes to KKOS, the same problem also co-channel interfering KFSH-FM, also at 95.9. At the time, Fiesta Mexicana owned by Califórmula a Tijuana station broadcast on 95.7, XHKY-FM. XHKY was causing interference to KKOS. Ultimately, KKOS and XHKY reached a deal, which was agreed to by the FCC and SCT; on September 15, 1995, XHKY Fiesta Mexicana moved to 99.3 at 25,000 watts, KKOS moved to 95.7 at 25,000 watts, and the previous occupant of 99.3, XHATE-FM in Tecate, moved to 95.3 MHz.
At 95.7 (first incarnation of New Country/Magic)
The day of the frequency change, KKOS became KUPR, still keeping the AAA format. On November 22, 1996, the station began stunting with country as "Your New Country, 95.7 KUPR". On March 5, 1997, the station flipped to Urban AC as Magic 95.7 under new callsign KMCG.
Mix/K-Joy/Kool/New Country (1998-2011)
The station was sold by Nationwide Communications to Jacor/Citicasters. On September 7, 1998, the "Magic" format would move to XHRM. After a 15-day period of simulcasting on both frequencies, on September 22, 95.7 flipped to Hot AC as "Mix 95.7" with the callsign changed to KMSX. The format was shifted to all-1980s' hits on November 11, 2000, a day after KBZT adopted the format. On November 21, 2001, KMSX swapped frequencies with KJQY and flipped to oldies as "K-Joy 95.7". On January 3, 2002, the station rebranded as "Kool 95.7". On January 5, 2004, “Kool” moved to XHHCR-FM 99.3, and 95.7 adopted XHHCR's country format as US 95.7. The station would rebrand as "New Country 95.7" in September 2008.
KOGO-FM (2011-12)
On November 7, 2011, at 7 a.m., after playing "The Dance" by Garth Brooks, 95.7 began simulcasting KOGO as "News/Talk FM 95.7 and AM 600 KOGO". On the 14th, KUSS changed their call letters to KOGO-FM. Unlike many news/talk stations, the FM addition did nothing to help KOGO's ratings; in fact, they declined after the addition of the simulcast, dropping from a 3.9 in the September 2011 Nielsen ratings to a 3.0 in the October 2012 ratings.
Holiday Stunt
The simulcast with KOGO ended on November 16, 2012 at 7 p.m., when KOGO-FM began stunting with Christmas music as Holiday 95.7.. The KOGO simulcast moved to KMYI's HD2 channel.
KISS-FM (2012-16)
On December 26, 2012, at 9:57 a.m., after playing "Silent Night" by Josh Groban, the station flipped to rhythmic oldies as "95.7 KISS-FM", with "Kiss" by Prince and "You Should Be Dancing" by the Bee Gees being the first two songs played. In mid-February 2013, the station began including more 1990s, 2000s and recurrent songs, and shifted towards rhythmic adult contemporary. On February 22, KOGO-FM changed their call letters to KSSX. After being jockless for the first three months, the station added Chio as their morning show host on April 8, as well as Sean Sarille in evenings, Shelley Wade in middays, Louie Cruz in afternoons and Beto Perez in nights. On November 16, 2013, KSSX flipped once again to Christmas music, but kept the "KISS-FM" name and "The Rhythm of San Diego" slogan. At Midnight on December 26, the station completely shifted to a rhythmic hot adult contemporary direction, dropping the pre-1989 songs from their playlist to focus on the 1990s, 2000s and current material, and changed their slogan to "Today's Rhythm and All the Best Throwbacks". Since then, KSSX has shifted towards rhythmic top 40 by incorporating more current hip hop, as XHITZ-FM de-emphasized hip hop in 2013 and began moving towards a more Mainstream Top 40 direction. On September 16, 2014, Clear Channel spun off its Radio and Communications division. The station then became a part of iHeartMedia.
Jam'n (2016-present)
On May 27, 2016, KSSX airstaff announced the station was going to start "Jam'n" for the 3-day weekend at 3 p.m. that day. At that time, after playing "Ignition" by R. Kelly, KSSX officially flipped to Urban Contemporary and rebranded as "Jam'n 95.7" under the direction of program director Rob Scorpio. "The Next Episode" by Dr. Dre and "Work" by Rihanna were the first two songs played. Under the new format, KSSX is the second station in San Diego to adopt the "Jammin'" brand, which was previously utilized by XHITZ off and on from the 1990s through the 2010s.
HD Programming
KSSX utilizes two HD subchannels. The HD1 subchannel is the same Urban radio format as its standard FM signal, as required by law. For the longest time, operation of the HD2 subchannel was contracted to the EMF, and like most HD capable urban stations, carried the Air 1 network. On February 1, 2019, operation of the HD2 subchannel passed to the Association For Community Education, which now repeats the programming of KMRO and carries that station's Spanish-language religious programming; in effect, now carrying the Nueva Vida network, the affiliation moved from AM station KSDO. FM translator K253AD, on 98.5 FM relays the HD2 subchannel, as KSSX already reaches North County, having Carlsbad as its city of license.
Competition
As of 2020, KSSX primarily competes with XHITZ-FM.
