I have tried many different 6sn7 tubes even the Tungsol round plate (known as the "Holy Grail" of tubes) but I have now found the best - Russian Military 1587 - These tubes are incredible the best of the best my system now sounds so good everything is real and life even my German shepeard thought that there was a fly buzzing around last night (me too for a few seconds) These tubes deliver everything, soundstage, presence, air, detail, warmth, life, beautiful tight deep bass and the range is limitless - I am using Cary 306 professional to DBX to Cary 300 SEI to Tannoy 15" Berkleys with Tannoy ST-200 super tweeters. Inter-connects are all Tyr balanced and Tyr Speaker biwired speaker cables. Power cords are all Lessloss - I hope that this is good info for all you tubies.
I assume you mean 1578 and not 1587. Yes, these surpass all NOS Raytheon, Sylvania, RCA, and new production types that I have tried. Authoritative, neutral across FR, detailed, smooth.
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