I have in my posession a vast array of tubes ranging from WE350B, Tung Sol round plates 6SN7 Black Glass, Ken Rad Black Glass VT-231, Sylvania JAN-CHS-VT231, Mullard GZ34, Sylvanis 6F6G, RCA VT-232 Grey Glass, Sylvaina 6SN7GT, Raytheon 6SN7-WGT, etc.... the list goes on and one.
All I can say is stop, step back, take a deep breath, and walk into the un-chartered territory that most of us have NOT known. It taken 3 years of owning a Supratek to get to this point. A complete round trip, back to where I started and the answer was sitting in my face as clear as daylight all along.
Other tubes may sound different, and yes they really sound different in my system, Each new tube inserted makes a difference. But at the end of the day the Supratek was optimised for a particular set of valves, yes folks, the ones included with the unit, when the unit arrived at your door step and you had that big grin on your face. When you opened the Federal Express box(s) with the included Sovtek 5AR4, Sovtek 6SN7 and Electro Harmonix 6L6, with a tear thinking, yes, yes the time has finally come.
Stop and listen to the original tubes, I think you may be pleasently surprised as to the calibre and the way it competes with NOS tubes. Best way to test this theory is to take all the NOS tubes out, dust off the Stock tubes sitting in the back drawer of a cupboard as mine where, plug them in and brace your self.
It does not get much better that that...Loads of Detail, Sonic Balance that does not tend to emphasise one area at expense of another, smooth and liquidy as one friend said today.
P.S. Remember to leave all the components on for at least 24 hours before passing judgement.
Happy Listening,
Fellow Audiophile (Learner)