Complex sentence: Two Oboe d'amore play the "love theme" from Act II. Akhnaten, Nefertiti and their six daughters, sing wordlessly in contemplation, they are oblivious of what happens outside of the palace.
Split into simpler sentences: Two Oboe d'amore play the "love theme" from Act II. We see Akhnaten, with Nefertiti and their six daughters, singing wordlessly in contemplation. It is obvious that they are oblivious of what happens outside of the palace.