What is the difference in the high end basses,I mean you have High end WARWICK, IBANEZ SR, ROSCOE, FONDORA, ECT. I mean in the hands of Michael Manring, Victor Wooten They all sound good.
Any high end bass "should" sound good in the hands of any bass player unless it is an absolute noob that is just learning how to play. With the differences, there are several little subtly differences. Circumference of neck, with of neck at the nut and base of the neck, type of woods used, type of electronics used, bridges used, shape of the basses, ergonomics of the basses, weight of the basses, types of finishes, types of wood used on the fret board, type of frets used and size of frets used. Some our hand made, others are mainly built using machines some have a mixture of both.
Like others have said, the price range really does vary as a result. So then it comes down to personal preferences. For me, let's take a high end Ibanez Soundgear. It's the lower end of high end basses in the 2k range. Compare it to a Music Man bass that is in the same price range. Let's say a Bongo. I loved the mid range Soundegar basses and used them for almost 20 years. Great basses for the money but I saw very little difference between them and their higher end stuff. The higher end Soundgears are made in Japan, and you only have a few finishes. I hate the bridges on them and the finish is really not that great for a high end bass. It is very similar to their mid grade line. Now I compare it too a Music Man Bongo. Much better electronics, better craftsmanship, better selection of colors and even what electronics I want in it. The width of the neck feel much more comfortable to me too. Now keep in mind, this is just my opinion. Someone else may hate Music Man basses but love high end Soundgears. But the finish, the fret work everything is completely different on these two basses. Even how and where they are made. Music Man basses are made here in the US as opposed to Japan. Music Man basses are made mostly by hand but some machine work is used for certain thing whereas Ibanez basses are made mainly with machines and less hands on work. Even on the high end stuff.
Really, the list is too long to say what the difference is between all of them because there are simply too many things. If you are wanting a high end bass, try a lot of them out, see which ones peak your interest and then learn about that specific brand as far as what option are available and then get what you like.