isolating a tube problem - ARC LS5 preamp

I cast my vote for tube rolling. When I replaced the Sovtecs in my ARC preamp, I was amazed at the improvement in imaging, subtle inner detail, transparency and dynamics. What to replace the Sovtecs with? After experimenting with several different types of 6DJ8s, I found that my unit sounded best with a combination of Siemens 7308/E188CC w/gold pins and either the Amperex 6922 PQ w/gold pins or the rare German-made Amperex 6DJ8 Orange globe logo w/steel pins. I found the Dutch Orange globes to be a bit too analytical in my preamp, but sound great in my ARC amp. The Amperex Bugle Boys and A-Frames are perhaps 90% as musical and detailed as their premium brothers at about half the price. Ditto for the Siemens 6922/ECC88 w/gold pins.
It's easy to understand why ARC had to go with a reliable, easily-replacable tube. However, you can do much better.

looks like the tubes are getting noisier and most of the tubes I've ordered have not arrived yet. Should I stop using the unit till the rest of the tubes arrive. SHould I unplug everything to swap out a tube or is a simple off on the power strip sufficient to change out tubes?

Thanks

Tom

I changed out six of 10 tubes, more to arrive

wow, what a difference, all the musicality of the preamp is back and more and in spades. Guess I'd been slowly lulled to sleep as the tubes went bad. Siemen's E88's and Valvo E188's sound pretty nice, need to add that expensive telefunken next.