I was curious if you could mix tubes. I have a Jolida 1301 intergrated with a tube pre and a SS amp. The tubes for the pre are 2 12ax7's. Well before I ever got my amp I bought a pair of Ei Elites that seemed to come highly recommend. Well I let them burn in for about 100hrs and then decided to see what the factory tubes sounded like. They are probably around 300+ hours on them. To my surprise I was floored by the sound of the factory tubes. The Ei's are VERY detailed and airy and all most too bright or detailed if you will. The stock tubes are for one thing louder than the Ei's and less bright or detailed. I am curious if the Ei's need more time to burn in or if this is what they sound like. I was wondering if I could put one of the Ei's in with one of the stock tubes to give it just a hint more detail with the added warmth of the stock tube. Is this possible to do? Mixing tubes.