Hi, I'm selling a pair of Mullard CV181 (=ECC32). They are variants of 6SN7, but with a higher mu rating. One of the best sounding 6SN7 variants ever made, these are very rare to obtain with a pair popping up every now and then on Tubeworld or eBay for $600-1000. I'm selling this pair for $450. However, if you are interested in a single tube, please ask and we could work out a deal.