Are Expensive Balanced Interconnects Necessary?

I have two pairs of balanced cables.  One pair was pretty expensive.  Actually now that I think about it was real expensive.  It definitely sounds better than the other cheaper one.  That is until I switch positions of the cables.  Then it doesn't sound better.  I keep switching the cables to try to figure out whats going on. But I haven't been able to.  Now, I've switched the cables so many times I can't remember which cable is the expensive one.  Can anyone help?  I'm to the point that I'm so frustrated I'm thinking of selling both of them and starting over.  This would be a real shame because one of the cables was pretty expensive.

On a more serious note, using a Cardas Clear XLR vs.  Mogomi XLR from my Atma-sphere pre to my Atma amp both of which meet the AES48 standard, I hear NO difference.   When using the same cables from my Denafrips DAC (don't know if Denafripts meets AES 48 but it is "balanced") I do hear a difference and improvememt.  More weight and transparency. So for me at least, the answer is it depends.  Sorry couldn't resist before :-)