I don't have to "imagine" it. I was a kid at the time, and I was there to experience it. And while you're dressing me down for my "cringing complaints" as a spoiled kid from the privileged, "in stereo where available" age, you might re-read my post where I complimented the SFX used in "The Doomsday Machine"—all done on the same limited dynamic range broadcast system and delivered over the same tiny speakers.It wasn't just dry. Imagine all sound having to go through a single 2-inch transistor-radio speaker, and you begin to get the idea. There was no stereo, no Dolby, no 5.0 / 7.0 Surround, no nothing. Just tinny-sounding lo-fi mono.
Any cringing complaints about sound quality come from the privileged perspective of home-theater stereo mixes with full-spectrum audio, none of which existed in broadcast television at the time the show was produced.