You absolutely can. It's not massive. But Spotify does sound muddy in comparison. And I'm not some crazy audiophile either. But I've definitely heard more clarity in some of my favourite songs and noticed certain parts of them that I've never noticed before just because I was using a FLAC vs using Spotify where I used to listen to it.

At a certain point, you're right you're not going to notice a difference on shitty speakers but there's something about Spotify's lossy compression that even at high you'll notice the difference between the two.