How old were you when audio gear first caught your interest?

I started DJ-ing at about 16 and purchase my first set of Technic SL1200 turntable at 18.  You couldn't tell me nothing, LOL.  That was 1980, damn I am getting old🙂

I built my first speakers when I was 17.

@faustuss 

"I'm right with you there! Lots of people though and because of municipal services reaching areas that couldn't previously be developed we're using up land fast."

Protect your precious plants. In 1978, when I bought this house, we had zero deer in my neighborhood, before they developed adjacent Scotch Plains. Now they are here and everywhere throughout our neighborhood every day, they like my back yard, often 6 of them resting there. 

We had a bad winter, Ice on top of 10" of snow, which was on top of prior 12" of snow. They ate all kinds of things they never ate before, azaleas, rhododendrons, forsythia, including bark of trees. They chewed our Hydrangeas down below ground level.

My father was a passionate audiophile who began his journey in 1948 with a single Altec 604B speaker. Growing up around his hi-fi system, I was exposed to high-quality sound from a very early age.

My own first stereo system appeared in my bedroom when I was 14, in 1967. It consisted of a used Marantz 8B amplifier, a Rek-O-Kut turntable, a Dynaco PAS-3X preamp that my father built, and a pair of JBL speakers.

Teenage electronics nerd in 1960s. Best friend and I would harvest Buick/Pontiac/Cadillac car radios available from junk yards for a few bucks. The audio sections were push-pull 6V6 with a heavy audio output transformer. To use these in our home "hi-fi" we had to power them on 120VAC. So, we'd build power supplies using power transformers from old Philco/ Zenith radios; these delivered 6.3 VAC for cathode heaters of car radio amp tubes, 5VAC for cathode heaters of the full-wave vacuum tube rectifier, which in turn provided filtered [choke and electrolytic condenser] higher DC voltage ["B+"] to the car radio amp tubes. 
The push-pull 6V6 amps put out 12 -20 decent watts that drove our home-built bass-reflex enclosed speakers, using drivers we'd got from Radio Shack, Allied, etc. 
Since then, gone thru AR3a, Dynaco amps, McIntosh, K-horns, B&W, Anthem...