Drawbacks of using large resistors in voltage divider?
The capacitance of your cable will form a RC lowpass filter with the resistors. With such high values, you should check if you still have the bandwidth you need. 

Look at the pF/m cable capacitance in the cable docs. If you don't have it, pick a datasheet for a cable of similar diameter and impedance.

At audio frequencies, impedance matching won't be a problem, so most likely there is no need to take this into account.

I forgot: if the measurement device at the other end of the cable has input noise current (ie, not a scope, but say, a BJT opamp) then high value resistors will increase noise. But high value resistors also make input protection a lot simpler, since they will limit the current...

Note if you want a 1:10 attenuation, why not use your scope's 1:10 probe?