Headphones. I'd use 5.1 Surround if I could (I have the speakers for it). But basically the flatmates complain when the volume is enough that I can pick up all the sound properly.
Only exception really is if I'm watching a film or tv program (not relevant to OP's question).
I also find the sound quality to be better with my headphone set up.
For the record:
NS1000s (second pair still working thankfully)
Xonar D2
FiiO e5
Turn on:
Dolby Headphone
8 Channel sound
ANR on headphones
In my own worldGot so spooked out by ghosts the other day in Skyrim...
kd
Same setup as me! Awesome awesome sound!