[quote name='Bill Fitzmaurice' timestamp='1506696630' post='3380515']
You use phantom power with mics that need it, typically condenser mics. SM58s aren't condenser mics. Most DIs aren't bothered being hooked up to phantom power anyway, since it's assumed that will be the case in many instances. The DI owners manual will say. BTW, I can't imagine using a DI on a guitar amp, and I don't recommend them for bass either. DIs don't capture the sound of the speaker.
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Bill's right about DI for bass not capturing the tone of your rig. However, I find it can be handy to add a little bass to the PA via the DI. It fattens the sound out front and gives a bit more weight to the sound from your rig on the stage. In larger venues and with a bigger PA, just mic up the cab.