tube recommendation please

BTW, I got a question in buying tube. On eBay, there are many single tubes. But most of the time people would need a match pair. The test score provided seems to be different depends on the instrument used. So .. if I buy a single tube, would it be very difficult to find one that match? It seems those score reflects the life of the tube. If I got un-matched tubes, does it means one may die earlier than the other? Or it will affect the sound in a negative way?

Thanks in advance.

There is no best tube, only a best tube that will allow you to achieve the sound that you want. I would suggest living with the pre-amp for a while and then describe in detail what attributes you would like to improve. If you find that your current tube set up is too lush and warm you will get remarkably different tube suggestion if you had posted too dry and analytical.

Looking at the specifications on your amp it has a gain of 12db. That would point to the 12au7's being your signal tubes as you are calling them. Really they are the first tubes in the gain stage and the 12ax7's are used as drivers. Unless there is a way of drastically reducing the gain of the 12ax7's or they attenuated at the output, but I don't think so. They will both be important. The 5AR4's are rectifiers. They will make a difference but your right for trying the other four first.

I have Mullard 4004 and Telefunken ribbed plates. They both have attributes that I really like. But the tubes that stay in my set-up the most are Full Music 12ax7's. They are really nice tube. IMHO

I think I will give the Psvane 12ax7's a try next. Happy rolling!

RCA 12AU7A clear tops with side getters. You won't need another pair for many years to come. For less money, consider Philips JAN 12au7a.