I purchased these 12 Tung-Sol New Production power tubes new as a tested matched set from Upscale Audio last year, for a Jadis Defy-7 amp. I only used these for about 1/2 hour while I was initially biasing my amp; they are virtually new. I was misinformed that I could change my amp from 6CA7s to 6550s. But it was modified before I bought it, and 6550s are not the best choice. So I have gone back to 6CA7s. These were bought as a matched set of 12, so the Bias, G2, Transconductance values for all 12 are close. My original cost from Upscale with shipping was $480. Also please note this is Free shipping within CONUS, or I'll deduct $30 if local in Las Vegas.