wualta- i can barely remember anything from the '70's :)
i do remember the sennheisers had yellow foam earpads, and they weren't very expensive and they didn't last very long, but sounded pretty good. the hp-1's were a lot better sounding but if i remember correctly they took awhile for my ears to get used to the fit. and they were pretty expensive- maybe $110 at the base px. i went through a phase where i kept upgrading speakers as they became available at the px, but i only bought the sennheiser and yamaha headphones.