Because your area of concern with respect to one or two subs is strictly music, I would suggest the answer depends primarily on your room's effect on the eveness of bass response from a single sub at you listening position.
The great advantage of multiple subs is in dealing with room nulls. If you do experience nulls, then a second sub can provide fill because you should be able to position it to have a peak in the range of the null from the other.
Cheers,
Gary
The great advantage of multiple subs is in dealing with room nulls. If you do experience nulls, then a second sub can provide fill because you should be able to position it to have a peak in the range of the null from the other.
Cheers,
Gary