As i am a trumpet player first and formost (recently passed my grade 8! ) i can read music competantly, and i have grade 5 music theory aswel. But i cant read music and play bass as i have been rather lazy and not learnt the fretboard as it were! So i feel that is holding me back a fair amount. But as i am fairly musical, i can get around that by using my ear. It hasnt held me back yet but if i ever wanted to try and do any pit work or anything a little more demanding, i cudnt really cud i ! Ah wel i dont really have the time or patience to learn!