help me select a single tube to "calm down" a preamp?


I have an Audio Research LS2B. It can get a tad "strident" in the upper mid on some recordings. I am now using a Siemens 7308 / E188cc and this is good, and often great tube for soundstaging and openess, but this tube also is a little noisy, mildly bright at times and is not the last word in bass performance. Would a Mullard suit the bill?.... How about an Amperex?....Your thoughts oh kind tube-0-philes :>)
audioman
audiojudge
Have you tried Kevin at upscale audio? www.upscaleaudio.com? This chap really knows his tubes and recommended a mullard for my SL-1 after I sold it to a friend...I'm sure there are others who know their tubes but Kevin comes to mind.....good luck and happy listening...Bluenose
Personaly I've had a tough time rolling tubes in my ARC LS-15. While there are a lot of good/great NOS tubes that will do the job, I find it difficult to get good examples. I still keep going back to the stock tubes. While ARC does charge a premium for their tubes, they are matched and tested. They have performed the best for me so far. At least you only have one tube to deal with. Maybe you should start with a fresh tube from ARC? Then you'll have an accurate bench mark for comparisons. Good luck....