A balding man is playing the drums, as another young man holding a guitar plugs in the amp.
The two men playing music are in a band together.
If a man is playing the drums but another man is just plugging in a guitar amp, then it can't be said with certainty that the  two men are playing music as the second person may not play any music. People can play music together even if they aren't in the same band.
exists e1 e2 s1 s2 x1 x2 x3 x4 x5 x6 x7 x8.(n_amp(x8) & n_drum(x3) & as(e1,x4) & in(e2,x8) & Theme(e2,x6) & Actor(e2,x5) & v_hold(e2) & n_plug(x6) & of(x6,x7) & n_guitar(x7) & (x4 = x5) & n_man(x4) & a_young(s2) & Theme(s2,x4) & -(x4 = x1) & n_man(x1) & n_man(x1) & a_young(s1) & Theme(s1,x1) & Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & of(x1,x2) & n_balding(x2))
exists e1 p1 s1 x1 x2 x3.(n_man(x1) & card_eq_2(x1) & a_together(s1) & Manner(p1,s1) & exists x4.(in(x1,x4) & n_band(x4)) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_music(x3) & (x1 = x2))