The Vox won't necessary make your stock pickups suddenly sing. The Vox is a hybrid, it's a tube pre-amp but still a SS power amp. The difference that the Seymour Duncan's will bring is definitely noticeable.
I have a Laney LX30R and it's more than enough to jam with, I don't have to set the volume beyond 3-4. Although, I jam on an open stage, so I don't know about a small room with maddening drum reverberations.
If you pick up both the Vox and the pickups that'll probably be the best outcome.
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