Hi guys, I play on a SWR sm400s and I always had problem to get a warm sound with this amp. I red on TB forums that the 12ax7 Groovetube sound bad in this amp and swapping the tube for a 5751 model will probably warm up the tone. I want to try this but I live in Quebec city Canada and I can't find this tube in any music or electronic store. Is there someone who know where I can find it in Canada? Thanks a lot!