"if I recall correctly the relief was built into the neck and there are no truss rods that can be used to adjust it."
Back in the mid-80s, Kawai came out with a line of graphite-necked basses (these were nothing like their Alembic inspired models BTW). I fell in love with the look and feel, but after a couple of days I noticed there was NO relief, and it buzzed like crazy on the lower frets. After weeks and weeks of trying to get the issue resolved, I finally had to raise a little hell when the store I bought it at was full of customers to get results. The result was, I got a different bass! (Guild Pilot) They gave me full credit for the Kawai. In the late 90s, I played a Modulus briefly, and that thing was great.