You risk horrible feedback if you try to run a mic into your guitar cab. Danelectro made one at one point with little mics on the tube - that idea never caught on, because it will squeal. Either use just a tube, or, use a vocal mic on a stand
I'm very close to getting myself a Rocktron Banshee, but I really need to know if I will be able to use it the way I'm planning to. I'll try to describe my intended use with the KPA below, maybe you guys can give me a hand trying this yourselves and telling me if it works:
Guitar
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-(KPA Input)-
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[KPA Green Screamer]
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[KPA Amp Block]
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-(KPA FX Loop Send)-
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** Rocktron Banshee **
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** Banshee tube **
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** Shure SM57 **
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-(KPA FX Return XLR, from Shure SM57)-
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[KPA Delay / Reverb]
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-(KPA Monitor Out)-
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** FRFR Speaker **
Note: I'm planning on placing the FX Loop in the "X" slot after the amp block in the KPA.