Grado Adaptor Cable 6.3mm to 3.5mm (15cm Length)

 
The title has the conversion about face. The Grado product converts from large to small aperture. Not the other way around.
This adaptor does not degrade the (high quality) sound of headphones in any way. It can be very difficult to find a quality 6.3 mm to 3.5 mm adapter. Most of these things are just very short socket to plug adapters that provide no strain relief. This Grado adaptor relieves the strain put on the 3.5mm plug because of the extra (approx. 6") cable length between the plug and the 6.3mm socket.  On the obverse it can be a little bulky but (IMO) makes perfect sense to protect your equipment. There are many other adapters out there, but these are well made to the highest quality specification. They also come from a company with a very well thought of reputation for their headphones.