Solude
Headphoneus Supremus
In my opinion the changes are subtle overall. A cable swap won't make the Senn 650 sound like a Grado RS1 for instance. It can shift aspects of the Senn 650 in a positive or negative way though.
A direct A/B comparison is worthless. Audio memory is too short and only a large shift in response would be noticable by swapping to and from. The only way I find reliable is to build a playlist and listen to it with one piece and take notes describing what you hear, then repeat the process with piece two. Then compare your notes to find the differences. Take notes of real things, like placement, volume of instruments compared to each other, blackness, visceral impact and such. Your notes will tell you what character each piece adds to the mix.
A direct A/B comparison is worthless. Audio memory is too short and only a large shift in response would be noticable by swapping to and from. The only way I find reliable is to build a playlist and listen to it with one piece and take notes describing what you hear, then repeat the process with piece two. Then compare your notes to find the differences. Take notes of real things, like placement, volume of instruments compared to each other, blackness, visceral impact and such. Your notes will tell you what character each piece adds to the mix.