I figured out the themes that comprise the first 30 seconds of "The Quest for Erebor" from DOS, which was thought as just "Opening Logos Theme". 1. The first six notes are a rhythmic variant of the the Erebor theme. 2. The next four notes after that are a darker variant of the Erebor "Endcap" that wasn't used very often in DOS. The pattern repeats multiple times before phasing out into the Shire theme. After all, the cue is called "The Quest for EREBOR", so it figures that the titular theme would at least appear somewhere prominent.
Adervae got a reaction from SafeUnderHill in The Themes of Howard Shore's The Hobbit