Are the "opamps" typically used for this application something like the DRV-134? I have heard that these are not transparent (but have not heard for myself). That said, doesn't THAT Corp make some THAT opamps that supposedly are quite transparent in this application? Transformers, no matter how expensive, still have non-linearities AFAIK, so in actuality may not really be better for this application...
That said, this entire post is from various reading and not based on personal experience. Quite possibly molto-FAIL
Just curious for any more explanation...