Hearing that audio requires a subscription to ReelRadio which is well worth the $15, I've been a member in the past but am not now.
WKBW (oh, here he goes AGAIN!) used to do two-fers called "on stage"...with concert crowd sfx between the two songs. That would've been my first exposure to a fantasy concert.
For anyone following The Celebrity Apprentice, you'd know that John Rich has been raising $$$$$ for St. Jude Children's Research Hospital in Memphis. Annual Radiothons have been the standard fundraising vehicle for the Hospital for years. We've been doing them in Pittsburgh since 1993, I'll bet 'YRK/'BEE have been involved that long too...but the entire "Country Cares for St. Jude Kids" effort began in 1989, spearheaded by Alabama's Randy Owen...as a fantasy country concert.
Maybe Randy Owen got the idea from Fantasy Park.