Well, as you have been around for 20 years you must have heard a lot of different bass sounds. This should already make it a bit more easy.
What I did when I bought my Fender from Ishibashi is just listen to as much of it on youtube to get warmed up so to speak
In my case I just had the Fender feaver so I didnt really care if it was either a bit heavy or required me to adapt my playing-style... I was always used to playing a bass with soapbar PU's which supported my thumb. With the jazz it has sharper edges on the PU, but I got used to that.Secondly, there are very knowledgeable people on this board that can tell you everything about different basses and their sounds.. There are some topics here that display some players' extravagant collections, and I'm sure that they are very willing to fill you in if there is a bass that you think you might be interested in!