I'll add myself as a data point: When at the Picplum office: Sennheiser HD-650's ( http://paulstamatiou.com/sennheiser-hd-650-headphones http://paulstamatiou.c

I'll add myself as a data point: When at the Picplum office: Sennheiser HD-650's ( http://paulstamatiou.com/sennheiser-hd-650-headphones http://paulstamatiou.com/sennheiser-hd-650-headphones ) hooked up to a FiiO E10 USB DAC. My cofounder has HD-555's hooked up to a (much more expensive) Peachtree Audio Nova amp. These HD's are open air so you can definitely hear what we're both listening to. We might have to switch to closed once we start growing the team so we dont annoy others. As for when I'm on the go, I have Etymotic hf3 earbuds with comply P-series foam tips. These sit very deep in the ear for maximum isolation though they can be uncomfortable to those not used to this style of earbud. You must also change the foam out every 3 months for a good fit.