Thanks for the elucidation of the Beijing rock scene to give perspective on the development of the more recent subterranean elements which are the concern of this page.
As for “citizen” avant-gardists, the first to come to mind would be in the form of authority defying subversiveness of Shostakovich.
As for China its two most famous classical pieces:
《梁祝》小提琴 协奏曲 Butterfly Lovers [梁祝 Liáng-Zhù] 梁祝 黄河 Concerto
Composed  by 何占豪 (He Zhanhao) & 陈钢先生 (Chen Gang)
Performed by 俞麗拿 Yu, Li-na (violin)
黄河協奏曲 Yellow River Concerto
Composed  and performed by 殷承宗 Yīn Chéngzōng (piano)
Both pieces fell foul of the Cultural Revolution - not to mention all the artists.
The first understandably so, being more apparently derived from folklore.
The latter, despite the presence of “East is Red” <<东方红 Dōngfāng Hóng>> thematic material it was eventually censored for it’s déclassé content.
Not until the 80’s Lina Yu could only play the recording for her children, very covertly, with their ear to the stereo speaker…
But, perhaps we will hear some of these themes in the approach to 08/08/08 ?!