I've already bought the SONIC-O-TOOL2 refill, do I need proVitamin too?

If the Reason's NN-XT is your main sampler, you won't need it: although proVitamin and SOT2 use different sample contents, they roughly sound in the same quality, maybe SOT2 provides a little better result.

But if you use other soft samplers too, like Virtual Sampler3 or Kontakt, proVitamin as a compatible sound font set might be useful for you.

Can I upload proVitamin into my Creative soundcard to replace the original GM set?

No. Unfortunately SBLive cards has a 128 MB patch limitation: that's why you can't upload proVitamin, it's 204 MB big.

Can I upload proVitamin into my Sound Blaster X-FI Fatality soundcard to replace the original GM set?

Yes! It seems the new Audigy cards support BIG soundfonts. You can replace the original GM set with proVitamin. It will sound much better!;-)

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