I personally think LPs sound better because what you're hearing is the actual music and not a digital resynthesis of it. I think there are subliminal qualities and cues in analog music reproduction (that certain 'breathiness' or 'air' as it's been called) that make LPs sound more natural to our ears. I don't really know how to describe it other than to say when you first cue an LP, just before the music starts you can hear "the room." That empty but not totally silent "space" that the music starts playing in a second or so later. That ambient
space is something digital recordings don't have. Digital is pristine. Almost too pure at times. (Which is why some noise often gets added to a digital mix just to remove some of that "too clean" quality.)
The other thing that I think makes a big difference is the mastering. With analog multitrack tape, there was always some slight "bleed" between the tracks. Nothing can be totally isolated on an analog master tape. Digital, on the other hand, totally isolates each track. I don't know if everybody hears it this way, but to me CDs have this odd effect of making each track sound like it's in a separate "layer."
Almost like there's separate "planes" that each of the tracks are on. And they're "stacked." You don't get a normal sense of 3D in the audio space. On some level you
have to connect the dots and create it yourself.
If analog's soundspace can be imagined as a cube, digital (again to my ears) sounds more like stacked 2D layers.
Something like this:
I don't know if it makes any sense the way I'm describing it, but to me it's almost like you're missing that continuous Z-axis
with digital. I'm aware of discreet layers
in the Z-axis of the sound when I pay attention to it. It doesn't "mush together" like an analog recording does. And like sound does in the real world.
And I think that on a largely subconscious level, a part of your brain detects it and thinks there's something wrong until you learn to ignore it. Much like you learn to ignore parallax when you wear glasses. You learn to look through them
rather than focus on the front or back of the lens surface.
I think you teach your brain to do something similar when listening to digital music playback.
Hope some of this makes sense. I have a hard time trying to communicate something as subjective as this.