Well the obvious answer to this question is...
Your cables were designed to sound a certain way with the connections that were provided.
Adding another piece of metal to the end would alter the manufactures design.
That being said, for certain applications couplers, right angles, adapters are ok. Such as home theater applications.
But, if you are really serious about your music (and I think you are because you asked the question), and you want the purist of sound , no adapter should be used.
My opinion.
Your cables were designed to sound a certain way with the connections that were provided.
Adding another piece of metal to the end would alter the manufactures design.
That being said, for certain applications couplers, right angles, adapters are ok. Such as home theater applications.
But, if you are really serious about your music (and I think you are because you asked the question), and you want the purist of sound , no adapter should be used.
My opinion.