I've been shopping for a combo amp that I like and the first one I bought was a gk mb115. I liked it but shortly after owning it for a couple weeks the tweeter started distorting so gc took it back. I was going to get another mb115 but started to like the hydrive stuff but most of them on eBay are refurbished or b-stock. I never see refurb or b-stock from other brands. Why is that. ?