I currently have my sub just in front of a chimney breast which is in the centre of the longer wall in my AV room/living room. It is on (carpeted) suspended wooden floorboards, but is on a marble slab and I have 6 halved squash balls providing isolation to a reasonable degree. The hearth in the chimney breast is being converted to an empty, plastered alcove which will be about 3ft wide, 18in deep and arched to a max of 3ft high. The hearth's base is brick over concrete and will be finished off with a decorative marble or stone slab. There will be a wood/board shelf near the top of the alcove for my centre speaker which will be directly below my plasma screen. The listening/viewing position is 8-9ft away, along the opposite wall. In terms of maximising the space in the room, it would be great if I could put my sub (XLS200DF) into the alcove and, on the face of it, I would expect a better result from the stone-brick-concrete base (and the fact that the sub is centrally positioned - I know bass is less directional but I have found I prefer the sub positioned between the fronts rather than to the sides). Are all of the above plus-points for the alcove location valid? If so, are they all going to be outweighed by any unforseen (by me) downsides to this location? Would I be better leaving it where it is/was? Or should I aim for 'anywhere out of the alcove'? Would the sides of the alcove be better than in the middle? I know the ultimate answer is 'try it and see' but a bit of guidance and pointers before I try to get too clever and move everything else around to accommodate this would be most appreciated. Supplimentary questions for bonus points: 1. The chimney breast/alcove are on the party wall with my neighbours. Is putting it in the alcove likely to transmit more or less bass to them? The house is 1930s brick built. 2. Should I be using the rubber feet or spikes if it is standing on either the current slab or the larger slab in the alcove? Many thanks in advance for your advice.