just replaced the stock 12ax7's with tung sol ecc803s reissues and there is a big improvement. i still have the stock electro-harmonix 6550's and 12at7's.
will replacing the 12at7's make that much of a difference in sound? thinking about slyvania gold brand 6201's -
http://www.upscaleaudio.com/product.asp?itemid=32&catid=45worth the expense or just stick with stock?