Most "1-hour loops" on sites like MuzicaHot are just ripped from YouTube. To ensure you’re getting the best audio quality (and not a compressed mess), find the original high-quality upload on YouTube first.
The opening track ( At Doom's Gate ) is designed to be repetitive and driving. Download Doom 1 Hour Loop MP3 – MuzicaHot
If you want the absolute best version of the original soundtrack, look for the "Doom Soundtrack - 25th Anniversary Remaster." It’s 훨씬 (much) cleaner than the 1993 files. Most "1-hour loops" on sites like MuzicaHot are
