Exactly. McCreary uses detuned instruments to create unease. If you compress that, you just get "muddy" audio. With the lossless track, you hear the specific dissonance. It makes your skin crawl.
Key tracks on the Season 6 soundtrack that feature prominently or capture the mood of this episode include:
To experience the nuanced instrumentation—including the penny whistle, fiddle, and Highland bagpipes—in lossless quality, you can purchase the official album from several hi-res retailers: