I've been shopping around online for a deal on a Crown xls402 amp. Most of the cheapest prices, which hover around 260$-280$, specify the listed product as B stock. This term has been thrown around the forums a few times that I've seen, but what exactly does it mean? Would this amp be of a lesser quality than, say, an "A" stock model? the a stock ones go for about 350-400$ as a reference; is it worth the higher price?