Back in the 70s I had the pro 4a, too. But you can't really wear those in public spaces, like the gym, unless you're looking for a lot of attention. I remember them becoming uncomfortable after only a few songs, though they sounded great.

I've tested several $25 to 150 lightweight portable headphones for use outside of the home and my favorite is the Koss Porta-Pro, which is about $50 new.

Another thing I like about Koss is their lifetime warranty. Over the years I've damaged the cord twice and then sent them to the Koss plant in Milwaukee, along with a $13 'handling' check. They attached new cords and shipped them back promptly, with new ear cushions too.