I've got an Xotic Effects RC Booster, and while it's a really awesome boost, really really transparent, and lets you add some extra EQ to your tone, I think the Keeley Katana is a better boost for blues type music. I don't think it's as transparent as the RC booster (still very transparent), but it adds this slight grit to the tone which is really pleasing.

It sounds great boosting drive pedals too!
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