MPU-401: The IRQ must still be cleared on reset.

src/sound/snd_mpu401.c

@@ -316,6 +316,9 @@ MPU401_Reset(mpu_t *mpu)
             mpu->ch_toref[i]                        = 4; /* Dummy reftable. */
     }
 
+    mpu->state.irq_pending       = 0;
+    MPU401_UpdateIRQ(mpu, 0);
+
     mpu->state.data_onoff                           = -1;
 
     mpu->state.req_mask                             = 0;