i do believe there are such cables... if i'm not wrong i've seen them before at places like luther and tymusic. but do take note of impedance and other crap
yeah pretty common... cheapest alternative has been stated: get a converter... worrying about line levels... wat are u using these cables for in the 1st place? ur acoustic guitar has an xlr output issit?
Use an XLR to XLR mic cable to connect to the mixer. You need the stereo cable to send out the unbalanced signal from the XLR out on the bass attack.
If you connect using the XLR to 1/4" cable, (assuming its a stereo connection) you will need to check the connections of the 1/4" input on the mixer first. Most 1/4" inputs on the mixer are wired send, receive, ground.