It would make a big difference for music. Great for movies too, but certainly a worthwhile investment for music too. I’ve done a side by side test of 2x1 + Sub vs 2x5 and I think the former combo comes out better. Whilst adding a sub to a pair of fives is also a noticeable enhancement. The difference is far leas noticeable than when adding to a pair of 1s. Some would say that would even be overkill. But it is certainly a diminishing return. Adding a sub to a pair of ones makes for a night and day difference. Go for it. You’ll not regret it.
Lounge: 5.1 Arc HT (2x Subs and 2xP5 rears) with LGOLED77CX. Kitchen: 2xOneW, 2xP3w with SubW. Bedroom: 2xP1s. Office/Studio: 2xP5w. Snug 2xP1s. Garage: 2xOneW. Also 3x Moves.