I haven't tried it (Luckily, I haven't had to), but in theory it should be possible to do. The theory is that the location of a properly set up sub, operating at the correct crossover, should not be audibly detectable. At least that's the theory, and that theory is completely contigent on the level and crossover frequency being low enough that localizing the source is nigh on impossible. In the real world (or more precisely, in your bedroom) results will vary, but to give it the best chance, you may have to run it at both a slightly reduced level and possibly lower crossover point. Since it sounds good where it is, just move it to the new location and try it out. Work the level down slowly til you feel it's either acceptable, or you hear the loss of the low end as just too great. If the former, you're done; if the latter, bring it up just as gradually as you went down, listening carefully to get it as close to level matched with your mains as you can. Once there, if the sub still doesn't integrate as well as you'd like, all you have left is lowering it's crossover point. Same shtick - lower gradually until you like it, or decide the loss is too great. With the lower crossover, you might then try bringing the level up a bit, but it might get a little bloated. It'll be tricky, either way, but... Theory says you can try!