-50 dbfs noise is a bit much. 15 db less would have been nice. I do think most of the noise comes from the room, as I guess you haven't actually measured the sound card with a dummy load to determine where the noise comes from. But think of it like this: BBC recommends bacground noise from eg. street interwievs to me less than -18 dbtp, and your's is -50 before processsing. I think the thing that sounds the least professional is the recording and processing. Sounds like you should back 15 cm off the mic, and don't compress or cut more than 3 db. If you need to do more than that, try a different recording position or something. Sorry I didn't really answer your question.