[jeffjazz]

I am a musician looking for a durable set of folding or lay flat closed back headphones to carry in a briefcase.
Using them with my cell phone and piano keyboards around gig time. Musician freindly cost! (under $100).
Thanks headphone experts!

 

[ruinedx]

https://www.amazon.com/Sennheiser-Professional-Headphone-Black-HD25/dp/B01CRI3UOU/

not exactly folding/lay flat but gonna be your best bang/buck by far. Cups are only a few inches in diameter. Good sounding and ultra durable.

 

[sduford]

Audio-Technica ATH-M30x
https://amzn.to/3hYtj23

 

[goldark]

I would go for an open-box pair of K371's for $90: https://www.proaudiostar.com/akg-k371.html

Foldable, easy to drive off a phone, great neutral tonality which makes it suitable for mixing/mastering/monitoring