I bought a Spector NS5CRFM natural oil about a year ago. I was not impressed with the natural oil sound of the Spector. It was very dull, had no bite and clarity and didn't seem as hi-fi as the others. At the time when I bought it I did not know this. The strings in the store were dead and so I thought that If I just bought it, took it home and change the strings everything would be OK. Well It wasn't I was pissed. To make a long,long story short I got a REFINISH!!! Had a glossy polyurethane finish put on it and BOY WHAT A Difference!!!!! I got it out of Pat Wilkins(Who does excellent work by the way) shop today and this thing kicks ass now. WALA, the clarity, the bite the slap tone is all there. I think it was well worth the money. Anyone who tells you that the finish on a bass has no effect on the tone, don't know what there talking about. It most definitely does and to all those thinking about a Spector Czech 5 I would recommend not getting the natural oil. But hey its up to you. You decide.