Hi.
Would appreciate any suggestions on how to deal with this cupboard which is at the back of the room. I've considered putting the door back on and putting a monster in front of it but because I don't really need the space, I'm wondering if I should just fill with some kind of acoustic material and make it a large bass trap, albeit being on only one side of the room. Symmetry? It does seem a common view that Symmetry is not so important where bass traps are concerned.

The room is 10FTx10FTx8ft and the cupboard is 15ins deep and 5FTx8ft.
Thanks.