I'm absolutely stuck with a demo song I have in mind.
I'm usually happy with the results I get, but it's the first black metal song I write and it turns out like absolute dogshit no matter what I try.
Both rythm and lead guitars sound so surprisingly bad I'm at my wit's ends. It can't be only because I'm tuned a whole step down, there's something fundamentally wrong, sound-wise, and I can't put my finger on.
Any idea to improve this? (other than delete the whole project because I suck at playing)
Here's the first minute of the demo song. I only recorded the first couple of bars with the lead guitar and didn't record the bass yet: 
https://vocaroo.com/1jETvckSA7T6
I'm using a Focusrite audio interface, FL Studio and Amplitube for the amp sim. All recorded pre-processing so I can tweak it. Feels like I used a baby monitor for recording.
For reference, I'm usually more into punk songs. Sorry if it sounds weird, I'm still learning to compose/play/record/mix: 
https://vocaroo.com/16oGTJcc6tHA