Music without lyrics as a political weapon? Definitely hard but has been done.

The russian componist Shostakovich living in the ear of Stalin had to compose a lot of pro-communistic works as all music was reviewed and censored by the government at that point in time. If it was subversive yud have a good change of being sent to the Goelags or such. The music he composed under this regime was very bombastic almost marching-like but he did manage to put or hide in some more subversive lines -only audible by the incrowd- and later on you can hear a shift in his music becoming much more liberal and free. Some of it was composed under the repression of the regime but wasn't released until it was safe to do so.

In general all cultural outlets are under threat in a dictatorial regime and every revolution is pushed with intellectuals and artist alike.

Obvioulsy lyrics are the most 'dangerous' and musicians have been imprisoned or killed for that. So whether music can change the world or not in a politcal sense, the people at power definitely percieve it to be a threat so the answer to your OW would be 'yes'.

On a side note: I always found the story of Victor Jara quite touching. A chilean teacher/musician/poet was brought to 'justice' under the regime of Pinochet and before his final execution he was beaten and tortured then his hands were broken and his executioners mocked him, daring him to play a song on his guitar. It is said he did sing -as a sign of will- but inevitably was gunned down and murdered as were thousands during the era.