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
Bill, while they probably won't hurt the amp, the tubes that you suggest are not direct substitutions and are not a good idea. They will change the operating parameters of the amp. If you want to change the sound, there are sufficient sonic differences within the 12AX7 and 5751 families to get you where you want to go.

The historically correct preamps for your amp are the CJ PV2ar (do not get the PV2 or PV2a, an original PV2ar will have black knobs) or a PV5. Both come up for less than $500.00 from time to time.