I would say yes, if you can go for a 5 string bass. If not you will be better off with B to D strings from a 5 string set but you will probably need to carefully ease the nut with a needle file to accommodate the thicker strings.
Talking of amps, if you have a 40W then I'd not be looking at anything as low as a 60W as the difference, depending on the make and model, may not be noticeable.
It depends on what you're going to be doing with it. Sort that out and come back and ask for a recommendation
Peter