What do you mean they require set up out of the box? Like putting in new strings and batteries for the pick ups? Also will an SX bass be a decent upgrade from a Squier(the only bass I own)?
Realistically speaking ANY cheap bass you buy will need a setup out of the box. Meaning strings, intonation, string height, possible fret work adjust high frets or sharp fret edges, etc.
It all just depends what your expectations and standards are for your basses. Someone with strict expectations is going to need more done to a cheap bass for it to be considered 'playable' than a person that's a newer player with less expectations and requirements for the bass.
They're all very playable out of the box, it just depends what your personal standards and expectations are.
