I am not an audiophile,just like music as it should sound,but I am listening to the Flying Pickets,an acapella group from the 80s,a song called "Only You". I find the cable from eBay makes it seem as if there is more bass,a fuller,warm sound with greater volume,as if you are closer to the music. You can still hear the different singers.
I think it is actually a good idea to have both cables as it depends on what the song is as to which cable suits best,but the new cable just seems to give you a more immersive experience,the B&O cable is for if you want a more clear sound as if you are listening in a studio.
As I say I am not as knowledgeable as some on here,a beginner,maybe some will disagree with me,but this is my take on it,I must also point out that I have only had these headphones for a few days,maybe it will change with burn in,I just know I love these headphones.
You should really find the Flying Pickets they are great on decent headphones,also Elvis with the Philharmonic Orchestra (really like Bridge Over Troubled Waters) & "Riding With The King" B.B.King & Eric Clapton sound amazing