TPA3255 shutting down on 48 volts. Heat sink is cool to the touch.

No problem! I had considered trying another one but I already had an IRS2092 I figured had more power anyway so I went that route instead.

My advice is to buy any of these chinese sold boards with caution and a good return system. Ebay is usually pretty safe. I just received six 3118 boards and only one or two worked and ALL were fake (30 watts mono instead of 60). They ended up refunding them. That may or may not have worked on Ali Express. Got to watch the chinese sellers. Lots of counterfeit and no QC garbage out there these days. It's gotten a lot worse recently.