This is not the last American audio cassette factory at all, as far as I know. Depending on what you consider a "factory", I'd still say that I know of at least two others in America.
I was just on the phone with someone over there last week. It's funny to see what Tricia Hedgepeth looks like. I have spoken to her on the phone so many times.
I don't think the tapes sound "digital", and I don't think they go without listening to the tapes at that company. They are very pre-occupied with copyright infringement, and I think they do listen pretty well for that at least. They may also take special care with me because I received a tape that had "ghost sounds" on it (the audio engineer's words). They didn't know where they came from. Instead of accepting their offer to do the whole thing again, I decided to keep the "ghost sounds" on the tape. But since then, they call me with concerns about various sounds they think might be unintended. It's funny, because the audio production guy is Asian, and there is a language barrier, so I have to explain what is intended and unintended very carefully.
There was one time where the tape I did with Phage Tapes (Blood Rhythms - "Nothing To Declare") took months upon months to be finished. Since that time, they have expanded considerably, and turn over projects within a month usually.
I honestly think that "Chrome" tapes are over-rated. I never get enough low end with those. I always go with Cobalt, and have not been dissatisfied. That may be why people think something from them sounds digital.
NAC also offers the service of producing audio on REEL TO REEL. For the record.
