Welcome!
I'm a retired civil engineer. Spent 8 years doing structural design, 3 years writing environmental permits, and 25 years reviewing plans for and inspecting various healthcare facilities.
Assembled a Hafler preamp and power amp (with help) and built transmission line cabinets from a kit I'd heard in 1980, but that's been it for me.
What speakers do you have? What upgrades are you thinking about? Some upgrades, like swapping out parts for better ones or adding a subwoofer, are straight forward. Beyond that it can quickly get into a crap shoot.
I'm a big proponent of the room itself. IMO most audiophiles way over invest in gear for the given room. Most listening rooms are too small, or poorly shaped, not sound insulated, and/or not dedicated to allow for treatments and proper setup. Suggest reading Floyd Toole's "Sound Reproduction" 3rd edition to learn how speakers/subwoofers behave in-room and the huge bass peaks/dips inherent to every residential room.
Am also a big proponent of active design, where low voltage signal is fed to a sophisticated crossover which feeds individual power amp channels for each driver. Undeniable design, cost, and sonic advantages. Active monitors are what studio professionals use to make your music. Unfortunately most audiophiles follow the hunter mentality, constantly on the prowl to add to their big fancy trophies, which actives don't support.
