It's a great amp gor HiFi speakers, I use it to drive a pair of Elac DBR62 and it works superbly. It doesn't even break a sweat, at almost full power it drains maybe 2-3 green lines from the bottom. Loads of power. I like it better than the Behringer A800 which I also have. I know it's not fair to compare a class D vs AB amp, but I'll do it just the same. :)
The A800 is more precise for sure but the s150 is more musical, full of midrange, and much more power. You can listen to it for longer. A800 has the highs more pronounced and is more analytical, the 150 is warmer. Peraonally I would go for the s150 any time. It also has much more headroom than the A800 does.
Protection relay works very good.
It's very very heavy at 12 kg. I have no complaints, i will probably try the s-75 next.