I'm interested in the Magic 5 Triplex Stereo Preamplifier but I'm also concerned about the availability of the tubes. Are the 12SN7GT and 6R7G/GT tubes a dime a dozen or are they hard to find? On a few sites I visited, they are either out of stock or not even listed. I am starting to get into tubes after building an Ear+. Thanks to Dr. Peppard for a great sounding, fun to build kit!