I have Mac,Rotel,B&K and Denon I just boughtCJ45a1

The CJ is my first tube amp.CJ tells us not to use any other tube combo's but the ones they put in their amp's I like the blues and have heard that a 12at7 in v1 and a 12ay7 in v3 is a good blues choice.But I don't want to hurt the amp.Will it? I'm useing a old Mac C24 I had laying around for a pre untell the wife releices my alowence and I can buy a tube pre (just kidding about the wife)But would like to find a nice tube pre for around $500.00. Any idea's? Thanks,Bill