Ctsooner, Aesthetix uses the same brands of tubes for their regular and Signature series. The Signature tubes may be more carefully selected, but they are current production tubes from the same suppliers. I just had my Aesthetix Rhea upgraded and spoke to Jim White about this.
If you own Aesthetix products, and want to use NOS tubes, they will refer you to Vintage Tube Services, as I indicated in my prior post on this thread.
If you own Aesthetix products, and want to use NOS tubes, they will refer you to Vintage Tube Services, as I indicated in my prior post on this thread.