Ive had my fretless Jazz bass for a couple of months and decided to change the strings from the stock 55 to 105 flats to Rotosound 40 to 100 half wounds (SM 55). The new strings really sing but I have some questions about the neck adjustment: With the new strings being lighter the neck has obviously straightened, the old Fender flats gave quite a bow. Its straightened to a point where its perfectly flat. Ive read somewhere that a fretless neck should be flat, unlike a fretted neck which should have a bow, is this true? With the neck flat I now get a fantastic action with no buzzes until where the 15th fret should be, and then its only a small buzz. After changing the strings the only setup change I had to make was to raise the height of the G string very slightly. Should a very small truss rod adjustment be made, or should I leave be?, after all I dont go that far up the neck very often.