http://www.watfordvalves.com/product_detail.asp?id=1290 Those in particular. I'm looking for something high gain, warm, musical, to fully retube the preamp in my Bogner XTC. The manual recommends Chinese tubes, and it currently has ARS 12AX7s in there. It sounds great but I can't help thinking the preamp tubes might sound a little... worn? (I got it used, from a studio, where it was used well) I thought a full retube of the preamp would be a good idea. Any advice?