I put together a stereo in high school. I had a pair of cheap Fisher speakers, which weren't terribly good. So I bought replacement tweeters and mids at a local shop and they were halfway decent. I ran them off a cheap Sherwood receiver, with an old Technics turntable, an Akai cassette deck and an old Sony CD player. A year later, I upgraded to a Kenwood receiver which was really nice. Actually, my parents are still using that Kenwood. It has a beefy power supply and has held up great for over 20 years.
My next major step was buying a Sony MDR-V6 that I used for a long time with a variety of gear. I still like them and they were only retired when I got a HD-650.
After that, I built a pair of Verhagen Ribbons and ran them off a compact Sony CD/receiver combo. Really nice sound, believe it or not.
From there, I picked up my first good headphone rig, a HD-650 powered by a Creek OBH-11. That got me into Head-Fi, where I quickly picked up a K-501, HF-1, and K-1000. That led to building the ProAc Response 2.5 clones and a pair of Moth Cicada drivers. And a whole lot else.
I think the journey is going to end once the Linkwitz Orion3 speakers are done. I have the parts aside from the cabinets. Still on the fence between building the cabinets or ordering them. I'll probably sell a few things and order them later this year. I'll drive those with a pair of Adcom GFA-2535 amps I picked up last year and use an Electra-Print Ultrapath preamp. I also have the preamp in parts - I just need to assemble it once the workshop is done. Also, I don't plan to buy any more headphones at the moment. Maybe if Sennheiser improves on the HD-800 or something else interesting turns up.