KAZZ-FM (95.5 mHz) was among the first group of low-powered FM stations licensed by the Federal Communications Commission in 1956 and 1957. Originally licensed to the Austin, Texas, market, the station began broadcasting afternoons and evenings on October 31, 1957. Its call letters reflected the musical tastes – big band and jazz – of its target audience, University of Texas students and faculty, for whom "cool jazz" – exemplified by acclaimed musicians Miles Davis, Stan Getz, Dave Brubeck, Chet Baker, and Bill Evans – was the current musical rage. In fact, KAZZ, pronounced to rhyme with "jazz", announced its launch via a small ad appearing in the October 31st edition of The University of Texas student newspaper, The Daily Texan. KAZZ, founded and initially owned by Austin businessman Frank L. Scofield, was co-located with Austin's first FM station, KHFI-FM, on the premises of Audioland, an audiophile equipment retailer in downtown Austin owned by Scofield business associate James Moore. Moore had launched KHFI-FM (which took its call letters from Audioland's parent company, Hi-Fi Incorporated), only a few months before KAZZ launched. In an unusual experiment, in November 1957, KAZZ and KHFI presented the first stereo broadcast in the Austin area; because both stations broadcast in monaural only, one station broadcast the left channel and the other broadcast the right channel of the stereo program. Of course, listeners needed two FM radios to hear the stereo effect, but selling newfangled FM radios was one of Moore's goals and brought customers to Audioland. FM radios at the time were expensive, and the best model Audioland sold, the Granco, cost $40, a hefty $435 in 2024 dollars.

KAZZ's first station manager was ex-University of Texas student Bill Oxley. Oxley's reign was short-lived, because only a few months after KAZZ's launch, Scofield sold the station to Moore, who promptly installed KHFI's manager, Rod Kennedy, as manager of both stations. Rod, later to become famous for his popular Chequered Flag folk cabaret in downtown Austin and as founder of both the Longhorn Jazz Festival and the Kerrville Folk Festival (which continues to this day), in turn bought KHFI from Moore in 1958.

Early on, KAZZ was making waves: from May 6 to June 6, 1958, national record label RCA Victor ran a high-stakes contest to promote TV star Dinah Shore's recording of Secret of Happiness, which was based on Chevrolet's Impala TV commercial theme made popular on The Dinah Shore Chevy Show. RCA awarded a 1958 Chevrolet Bel Air Impala convertible to the person writing the best letter describing his or her secret formula for success. Entries from the public were submmitted through local radio station announcers (better known to the public as disc jockeys or "deejays"). And the deejay who submitted the winning entry also was awarded a Chevrolet Bel Air Impala convertible. Although over 1,000 deejays submitted entries on behalf of their listeners – there were more than 700,000 entries from across the U.S. – the prize winning letter was written by Austin resident Peggy Todd, whose entry was submitted by KAZZ-FM deejay Bill Jackson. Both were awarded identical Impala convertibles. The win was a big coup for KAZZ, then not even a year old.

Rod Kennedy acquired KHFI from Moore's Audioland Broadcasting Company in 1958 and in turn sold the station to James Kingsbury's Southwest Republic Corporation in August 1964. Meanwhile, at the end of July 1961, Moore moved KAZZ-FM's facilities from Hi-Fi Inc.'s offices at 3004 Guadalupe to the Perry Brooks Building at 720 Brazos Street, a block east of Congress Avenue, in the shadow of the state capitol building in downtown Austin. The station's 250 watt broadcast transmitter occupied a locked room off the Perry Brooks Building's stair well, half a flight down from the station's 10th floor studio, and the 23-foot 4-bay antenna, which multiplied the transmitter's output to an effective radiated power of 840 watts, was mounted on the building's roof. The entire electrical output of KAZZ's antenna barely exceeded a dozen 60-watt light bulbs. The antenna mount proved fragile: in September 1961, Austin experienced high winds attributable to Hurricane Carla, which wrought major destruction along the Texas coastline, that knocked down KAZZ's antenna. It took days to get the station back on the air using a temporary antenna rig. A month later, in October 1961, Moore sold KAZZ-FM and its parent Audioland Broadcasting Company to Earl Podolnick and Wroe Owen, then president and vice president, respectively, of the Trans-Texas movie theater chain. In July 1964, Austin restaurateur Monroe Lopez bought KAZZ-FM and Audioland Broadcasting Company from Podolnick and Owens.

Initially, after the move to the Perry Brooks Building, KAZZ occupied two-room suite 1014, next to the building's elevator bank, but by the end of 1964 had relocated across the hall to suite 1003 (housing the administrative office and main studio control room) and suite 1004 (housing the reception room/music library and a production room for recording commercials and public service announcements). The station's AP news wire – a clickety-clacking teletype machine – was housed alongside the transmitter in the mechanical room behind the elevator bank.

Concurrently with his purchase of KAZZ and in part because of his desire to provide Spanish-language radio programming to Austin's underserved Latino community, Lopez hired Gib Devine as station manager. Devine had extensive experience, through his Austin-based Language Arts, Inc., producing English-Spanish language courses on audio tape for high schools and colleges. Devine immediately dropped KAZZ's big band and jazz format that had launched the station in 1957 in favor of a block programmingA type of radio programming that varies musical genre – for example, rock, country, jazz, folk – from time block to time block during the broadcast day, the musical genre of each time block designed to appeal to a different audience demographic. format, hoping musical diversity would attract more advertisers. At Lopez's direction, Devine added a Latino music block to start each morning. The typical KAZZ broadcast day in mid-1964 included blocks featuring Spanish-language pop hits, easy listening and pop standards by artists such as Mantovani and Sinatra, a smattering of light classical music, entire showtune and movie soundtrack albums, and nighttime folk, country, and jazz blocks. Unlike many AM radio stations that are limited to a sunrise-to-sunset broadcast day to avoid nighttime atmospheric interference with each other, all FM stations are licensed for 'round-the-clock operation. Nonetheless, to save money and because the all-night audience for FM radio was low at the time, in fall 1964, KAZZ's broadcast day was 6 AM to 1 AM. Having briefly flirted with a jazz and folk program from 1 AM to 6 AM in late 1965, on January 1, 1967, KAZZ began 24 hour programming featuring what program director Sam Hallman described as "controlled" top 40 music with a little folk thrown in for good measure. This time, the 24-hour format stuck but soon the rock and folk gave way to an all night R&B program.

But back in spring 1964, future Sonobeat co-founder Bill Josey Sr. was commuting weekly from the family home in Austin to Galveston, Texas, where he served as sales manager for top 40 AM station KILEKILE was pronounced "K-Isle" by the station's deejays, reflecting that the station's home city, Galveston, was a major island resort, island sitting 50 miles southeast of Houston on the Texas Gulf Coast.. At the same time, future Sonobeat co-founder Bill Josey Jr. was finishing his senior year at Travis High School in Austin. On his weekend trips home, Bill Sr. brought Bill Jr. spare "promo" copies of hot new rock 'n' roll singles that KILE received free from record companies. Bill Jr. was fascinated with his dad's stories of the deejays at the resort island radio station and entertained his siblings by spinning the promo singles on the family's living room hi-fi, adding mock radio deejay patter between records.

Bill Sr. arranged for Bill Jr. to take a two-month summer apprenticeship at KILE following high school graduation, and there Bill Jr. got a crash course in how local commercials were produced, how local news was gathered and reported, and finally how to "deejay" – select and cue up records, use the control board, launch commercials on tape cartridge players, speak into the microphone without (much) fear, and get all those elements synchronized. Halfway through his KILE summer apprenticeship, Bill Jr. landed the early-morning Sunday time slot. It was common during the '60s, radio's "golden age" of personality-driven music programs, for deejays to use "air names" concocted for dramatic effect (for example, KILE's afternoon drive-time deejay went by the name "Roland Holmes", a clever soundalike for "rollin' home") as well as to protect their real identities from often overly-zealous fans. To choose his "air name", Bill Jr. wrote dozens of last names he liked on slips of paper and threw them into a hat; then he randomly pulled a slip – on which he'd written "Kelly" in homage to Pogo cartoonist Walt Kelly, but that he decided to spell as "Kelley" – that had been caught in the hat's rim, inspiring his entire air name. When his summer internship at KILE ended in August 1964, Bill Jr. returned to Austin to start college at The University of Texas. Jobless, but now with a potential broadcast career percolating in his blood, he solicited work at Austin's only top 40 station, KNOW AM (now adult pop hits station KJFK). Turned away from KNOW as too inexperienced, and at Bill Sr.'s suggestion, Bill Jr. recorded a short demo tape that he sent to other Austin radio stations, including Austin's oddball block-programmed KAZZ-FM.