Sennheiser HD25 (not the HD25s) are fantastic. They probably still cost just over £100 but they are honestly the nicest sounding 'phones below £300!
They are closed back, so 99% of the sound actually goes into your ears rather than the environment. They can also handle a lot of power. Far more than needed to deafen you ;)
Plugged in to a decent amp, they are awesome. They also work well (with a 3.5mm adapter) in the headphone outs of most portable devices. Ipods are a bit quiet through them though.
**EDIT** They are also extremely comfortable. May not seem like an important point, until you wear uncomfortable 'phones for more than 30 minutes!
They are closed back, so 99% of the sound actually goes into your ears rather than the environment. They can also handle a lot of power. Far more than needed to deafen you ;)
Plugged in to a decent amp, they are awesome. They also work well (with a 3.5mm adapter) in the headphone outs of most portable devices. Ipods are a bit quiet through them though.
**EDIT** They are also extremely comfortable. May not seem like an important point, until you wear uncomfortable 'phones for more than 30 minutes!