Just do some research and get a cheap class D amp off a chinese website. I forgot the one I chose(I'm at work now), but other than some sparks if you jiggle the power connector(haha seriously. can be fixed with a tiny bit of effort), it is an amazing little amp. It also supports optical and bluetooth connections which is really nice.

I put my efforts into building speakers instead. I got a cheap kit (https://www.diysoundgroup.com/overnight-sensations.html) and spent my time learning how to apply a french polish finish. I really enjoyed learning french polishing. It's one of those things that when you finally get it, it becomes immensely satisfying. Yeah, shellac isn't the most durable finish, but it sure is pretty.

If you are looking for something already built, the eBay/aliexpress shops of the Shenzhen companies often have the option of selling you a complete amplifier made up of their modules. Which will probably end up cheaper than getting all the parts yourself...

I'm not sure I understand your question; what do you mean by "but should really put their time elsewhere"?

Are you asking for an amplifier that would deliver similar performance to this, because you don't have the time to build one, or that you suspect you'll come out ahead on build vs buy because of the price you value your time at?

There are these I've been tempted to try out that use the same chip (and a low noise pre amp), but unfortunately I have two perfectly functioning amplifiers already :-) (and a set of powered edifier speakers in the mail - I have a problem). https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m...

They have a switch mode power supply instead of the toroidal in the IEEE article, so in theory more noise - in real life? probably doesn't matter. THD < 0.01% at 30W, frequency response is +- 1db, the days of having to spend any money for an amp seem gone, < $70

I was planning to build my own system, I wanted a DAC + Tube Preamp + AB Amp. You can get a really good DAC board from https://www.hifiberry.com/shop/boards/hifiberry-dac-dsp/ and for the rest of the system I was going to get it from http://glass-ware.stores.yahoo.net/newhardware.html.

People discard old electronics, some of them of very good quality. Short of that, you can find this stuff on craigslist. The used value of some nice gear is very modest. I'm running one set of my chromecast audio linked speakers on a vintage Pioneer receiver with those funky proprietary speaker jacks I found on the "take it or leave it" table at the dump. I also found a McIntosh with a funky combination of a tube tuner and transistor amp literally on the scrap metal pile. But it needs new power caps.