A friend of mine has professional gigs with bass ukulele several nights a week. One Kala (fretless) performs ok, but there are problems with the piezo pick up on the back up instrument. No one seems to be able to adjust it so that there is good output across all four strings. I believe that issue with the piezo has been discussed here previously. The back up instrument has been replaced by Kala several times. Requirements are hollowbody acoustic (no solidbody) and fretless with pick up. What would be a step up instrument or are there any higher end Bass Ukulele makers? Thanks in advance for some pointers!