Try contacting Andy Bowman at Vintage Tube Services. He sounds as though he has been around for a while and he is both patient and very helpful. I have a Modwright modded Oppo 105D and I struggled to find the right tubes. Andy was very helpful in steering me through the congested 6sn7 tube market. The link to his sight is http://vintagetubeservices.com/mini-tubes-2/
Andy ships when he say he will and I believe he may allow you to return tubes not to your liking. Good luck, I feel, or did feel, your pain in pursuing this endeavor. Good luck.
Andy ships when he say he will and I believe he may allow you to return tubes not to your liking. Good luck, I feel, or did feel, your pain in pursuing this endeavor. Good luck.