Excerpt: An unusual feature of the Sennheiser HD 650 headphones is that the cables can be unplugged for easy replacement should the conductors ever fracture under physical stress in future years. They are quite thick cables, too, and three metres long, terminating in a 6.5mm plug. The only accessory is a 6.5mm to 3.5mm adaptor cable so you can use the headphones with a portable device or a computer.
Pros: Superb no-compromise sound, Very comfortable to wear, Main plug is 6.5mm
Summary: First things first. Do not be deceived by the 3.5mm jack adaptor – these are not headphones you want to plug into your iPod. They’re just too good. You need an amp to tease the most out of the HD-650s, and preferably a lossless audio source. Ideally it would be a very good amp, backed by a very good CD player, and preferably with some very, very good audio cabling on top. Music in three dimensions These are, simply, monstrously good.