I have just bought a denon 2311 and am thinking of FINALLY splashing out on a sub. I have mordaunt short 914i floorstanders and matching and matching centre n standmounts. Any suggestions for a good sub that would fill the gap? I don't want to spend more than I have too but I don't want one that will start making mechanical noises or clipping when things get oomphy as my first sub did. Is a 150watt going to be enough or should I be looking at a 250? Seen a wharfedale sw250 for £300. Any good for me? Could I do better for a similar amount?