I & W “Naked as We Came”:
I think I’m hearing a stereo mic technique - very subtle right to left movement. Maybe the left mic picking up more of the low strings and the right mic picking up the highs? Could be XY in a vertical rather than horizontal plane? They are panned pretty narrow, but it’s enough to give some left to right movement as the arpeggios are played from low to high strings.
Sounds like a very tight, dry room sound on the guitar.
The depth we’re hearing is probably a combination of 2 things. The guitar mic scheme has been compressed and picked up the room ambience, pushing it further back, and the vocals have a lot of “air” - high frequency emphasis and and good amount of lows too - to bring them right forward in the mix.
TTMOE "A Lion’s Heart"
I’m betting the guitar was recorded with a single close mic, but also has distant stereo room mics on it, because when the guitarist hits the strings harder, the room mic “opens up” across the stereo spectrum - that’s the movement I hear, anyway. The vocal sounds like it has a stereo plate on it, with a good amount of pre-delay - around 100ms to keep the vocal right up front, but give some space around it.
Sufjan Stevens “Drawn from the Blood”
The guitar has a tight room verb that has no pre-delay and pretty much all early reflections, panned to the opposite side of the source guitar to give some width. The vocals probably have the same early reflections, just lower in the mix and double tracked in stereo.
SS - “No Shadow…”
This acoustic guitar sounds double-tracked to me, rather than artificially doubled. If you listen closely, at the beginning of the song, you can hear that only the left channel guitar has the fret squeaks/ neck movement artifacts left in. It sounds like they have been edited out of the guitar on the right. Later on, you hear some fret squeaks from the right guitar, but not at the same time as the left, which you would expect to hear with a doubled part.
This seems like a very clever tactic to keep an organic sensibility and a sense of realism while not allowing those artifacts to be overbearing or distracting.
Vocals are obviously doubled - tight early reflection room sounds on both to bind the mix together (or possibly jus the sound of a tight room emphasised by compression).