First decent hi-fi system and rediscovering metal albums

I have wanted a decent music system forever but always thought it to be expensive. I found an amazing deal and so now I'm a proud owner of an amp, CD player and speakers instead of a bluetooth speaker!

I have pulled my CD's from the attic and I am shocked! There is such a difference in production of albums. I never noticed it that much, even with decent headphones but the differences are vast. I have particularly been enjoying anything by Ayreon and Opeth, although Watershed which has never been a favorite - it sounds amazing. Last two releases by Gorguts are mind-blowing in a different, visceral and hypnotizing way. I am losing sleep because I can't stop listening to music at night...

Are there any heavy metal albums (thrash, death, prog - does't really matter) that you can recommend that sound excellent through a decent system?

EDIT:
Thank you all so much for the great suggestions! This will keep me busy for some time. :-)