according to http://www.audiophilia.com/hardware/power1.htm it appears they were Sovtek.
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If the E188CCs have the seamed top and gold pins, they are definitely NOT Sovteks. I remember reading somewhere that Gold Aero used to relabel tubes from other sources. (Not 100% positive) They are probably not Sylvania either. But these could be any of the NOS tubes. It would help if you have some pictures so we can at least compare the physical structures and look for signs so we can make some educated guesses. Look between the pins at the bottom. Is there a number in the center of the glass? Is there a dimond shape enveloping the number? Are there any type of code etched on the glass anywhere? These will help solve your mystery.
My SFD 2 Mk II came with a set of 6922s/E88CC that has gold colored "Sonic Frontier" label on them and "Made in Russia" in fine print across the bottom, not Gold Aero tubes.