There are different ways to get a great heavy sound. You can use pedals like distortion or fuzz with a clean or low gain amps. But if you want to get a really heavy metal sound, then you need a high gain amp. 

Check out some of the best metal amps.

With high gain amp you are able to dial a heavy sound with just an amp and then add some overdrive to make it tight and boosted. Almos every amp has different channels. So, you have options from clean, heavy and ultra or something similar.

Also, you must decide what type of amp you need - solid state, modeling, hybrid or tube. The best of all is tube amps, because it has a natural sound, but they are more expensive. Hybrid is also a great choice, because it has tubes.

But for home and practicing solid state and modeling amps are very good. Great thing is that you can get a heavy, metal sound form any types of amps.