Welcome!
Not to be a total snob, but high-end audio and DIY is pretty much an oxymoron. Of course it depends on how you define each term. High-end IMO isn't necessarily expensive, but more about knowing what you're doing (listening, room setup/design, equipment selection). Have a friend who routinely embarrasses our small audio club with his off the wall, relatively inexpensive gear. On the other hand most audiophiles way over invest in gear for the given room (too small, poorly shaped, not insulated, untreated). It's hard to achieve world class sound from DIY. Trying to do so is an insult to those top manufacturers who have invested decades into R&D, manufacturing, QA, etc.
Can DIY get you to 80% of the high-end of audio? With enough knowledge, perhaps. But so can a $5000 off the shelf setup. Most top manufacturers spend a lifetime trying to reach the highest pinnacle of a single aspect of audio (amps, speakers, a source, etc.). It's never been a better time to find value with off the shelf gear, check out the Cheap and Cheerful circle. With CD quality streaming of millions of albums available for $20/month, coming up with a library has never been more affordable. And active speakers can make quality sound downright cheap.
