Shure sm58 through Marshall AVT150X
I've just received my Shure sm58 and i assumed i would have enough volume from my 150-Watt ValveState guitar amp. But it turns out that the only way for me to get substantial volume from it is to funnel the sound to the microphone using my hand, and the turn the amp up higher than i've EVER dared to when using a guitar through it, which is so high there's audible noise which has no relevance to the position of the microphone. I would have thought a 150-Watt guitar amp would be enough, but does it sound like there's something wrong with the microphone/cable, or do you always need a PA loudspeaker? Can anyone help?