To be honest ... I would call that "audiophoolery". In my experience the benefits would be so trivial as to be unnoticeable without test equipment, and certainly not worth the financial investment... especially if it results in side effects as my friend in the other thread encountered.
Audio, especially at line level, is easy. On the EM spectrum it is but a tiny slice right at the bottom of the bandwidth chart. There's no magic... just plain old common sense design.
While it's important to know what you're doing and why, and how to be safe doing it, it is generally either beneficial or not worse at least to use a balanced style interconnect scheme appropriate to any combination of balanced/unbalanced connection.