HiFi Kit Building- have you ever built any hifi gear?

I can recommend any project from diyAudio.com. They are great folks, as are the customers who share experiences in the online forums. Great way to deepen your understanding of electronics, as well as your appreciation for how damn much a chassis costs and how much (or little) you can spend on parts. How can a resistor cost anywhere from 10 cents to $5 each, or a capacitor from a couple of bucks to $50 and more? Wild. If you do decide to venture into DIY, I’d suggest buying a complete kit. They do all the component selection for you and a good result is more likely. Cheers!

+1 on diyaudio.

Nelson Pass (the master himself) is active there and he contributed many designs. You can literally buy a kit Class A amplifier designed by Nelson Pass for a low to mid 3 figure amount in the diyaudio store, and you’ll even learn something (likely many things) building it.

+1 on Diyaudio too. Completed multiple builds. The Pass clone amps sound wonderful. Very good build guides also and a community willing to assist. They do take time and assume basic soldering and troubleshooting skills.

I’ve home-built multiple Dynaco amps and one FM tuner [Hafler designed?].  Both the building process and the end-point equipment have provided much pleasure over decades, and saved a lot of $$$. I've retired the PAT-5 preamp and an FM-5 tuner.

However my Dynaco Stereo400 power amp—built while I was a poor grad student at UT Austin 50 years ago—still performs to high standards in our music / theater room alongside Anthem P5 and McIntosh MC402 power amps costing in excess of 10 times than the Stereo400!

True… the Stereo400 has limitations, e.g., no balanced XLR, only RCA inputs, which can introduce barely audible 60Hz hum if not routed from the pre-amp/processor with care; but it’s a piece of cake to route a cable an inch or two and see the hum go away.

I would challenge anyone to hear differences [in blind audition] among my power amps.

Another bonus for techies: the Stereo400 user manual is NOT SHY about touting the amp’s performance specs! If you want to know why this amp does not hiccup during overdrive, nor damage your speakers, just read the manual and be in awe! 
Neither of my high-end power amps provide anything close to that experience.

I build from scratch.  You need some understanding of how tube amps work but it saves money.