Excellent. Please explain what you did, so that we can examine your methodology. The fact that you do not know which codec Spotify uses tells me a lot.
Well if you have nothing better to do with your time:
I have several times used the Foobar
ABX comparator plugin. I've also done various 'listening tests' online. On a lesser level I sometimes have a friend load a few versions (e.g. empty3, redbook, & hi-res) of a (volume leveled) file in foobar and have him play them randomly while I'm blind-folded. Then we swap over.
So now we both have a good general idea of what we can hear and where we struggle to hear clear differences. Sometimes 320kbps sounds OK to me, for playing in the background, but I chose to collect hi-res music rather than lossy files and I don't use Spotify or similar products. That is not a criticism just a personal preference. I listen to the radio in the car, but that is because the car's CD player is crap. I'm not saying my choices are superior to anyone else's, they are just a little different. My energy goes into my hi-res library rather than bothering with music in the car/kitchen. Just different priorities that's all. No big deal, so why are you guys getting all defensive about your use of lossy files?
I wont be wasting time with any more detail than this, I have a life
Actually, there is something that I find really obnoxious, not lossy files: if the original was well mastered they can be fine, in their place. But bad modern mastering techniques, using too much compression, as in 'loudness wars' really insult my ears. I will turn down, turn off, or delete ear-bleed (e.g. DR5) files!
As for not knowing what codec Spotify uses: Well, it uses some variation of 'empty3' right?
AAC, ogg Vorbis or whatever, is immaterial to me. I don't have any use for Spotify, nor empty3 in general. However, I respect anyone's choice to be satisfied with lossy files, especially in non-critical listening situations: in the car/kitchen etc..