Listening to headphones at low volume is fine, it’s when you dial up the volume that it becomes a problem. I also recommend open head phones instead of in ear headphones if possible. The Sennheiser HD800/s are excellent. Others, that I’ve enjoyed at the Grado PS500e, GH1 and GS1000e. Grado headphones are just very natural and musical and they emphasize the upper range so it helps people like us with some hearing lost. :) The top of end Grado PS2000e is fantastic but out of your price range. Btw, If you look on
www.massdrop.com they have some great deals on headphones. They recently or still have the Massdrop Sennheiser HD6xx (same as the HD600) at $250 which is a bargain. This has been my goto headphone when I can’t listen to the stereo late at night. One the best value in audio if you ask me. Right now, they have the Massdrop Focal Elex which seem very nice. Massdrop keeps rotating in new headphones so keep your eyes on the site. Good luck!