If by "RCA connection" you mean an analog link, then it's not doing a perfect transfer. It might be "proper" and good enough, depending on what your ears tell you.
If by "RCA connection" you mean that you have a 7-pin-to-coax cable (either Sony's or our's), then if the DAT recording was made as 44.1/16, and as long as the CD recorder isn't resampling, chances are good that it's a perfect transfer.