10 major/significant phases to my system since I was a teenager in the early 70's. My first stereo technically was a Magnavox stereo phonograph with ceramic cartridge back in the 60's when i was a kid.
First real component system in 1977. This consisted of Lafayette Criterion integrated amp and tuner, tt, and speakers that used the ESS Heil air motion transformer tweeters which I used to fry quite often.
The most consistent mainstay in my system has been Ohm Acoustics speakers. I acquired a pair of Ohm L's in 1978 and still run these (recently refurbished and custom upgraded). I currently own 3 separate pair of Ohms along with a pair of Dynaudios, a pair of Triangles, and a pair of Realistic minimus 7s.
I'd estimate 4-5 times as many actual component changes have occured along the way, but whose counting?