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

Yes. Stated with a Hafler dh500 modification, then rebuilding my old Maggies' crossovers and to a whole preamp (tubes for hifi sp14)  Best result, I've learned what the components do and have started modding them for my taste. For 3xample, adding a remote volume control to the preamp. Next step, the GR Research xoxer mod for the Maggie's. 

I started with a Heathkit multiband radio, then I built almost everything David Hafler kit and the last kit I built was the Dynaco Stereo 400 with the meters (of course).

I built the CSS 1TDX and 2TDX speaker kits.  They have a lot of bang for the buck, and it was fun.

Indeed.  Just completed a Troels Gravesen designed, 3 way Scanspeak speaker set.  They sit next to a component rack i built with the system IC loom and speaker cables based on designs by @williewonka here on AG.