The Grade B Shuguang tubes aren't defective. They're just a lower quality tube. Shuguang matches each pair, and the tolerance differences determine which tubes will be Grade A, B, etc. I also use the Shuguang Black Bottle 300B Treasure tubes, and have had no issues with them, and they sound very good. Very clean and clear, with pretty decent bass for a 300B.
I know Grant Fidelity has the Treasure tubes. I think others do, too. The only exclusivity Grant has with tube distribution, I believe, is with the Shuguang Psvane 845.
You can find them cheaper than 600/pr, but beware. You may not be getting Grade A. If you go with Shuguang, buy from a North American retailer. Shuguang routinely exports their best tubes, and keep the lesser quality ones in China/Asia. So, if you go looking on ebay or something like that, and find a pair for 200 bucks, don't think for a second that you're getting a great deal from the guy in Shanghai.
I know Grant Fidelity has the Treasure tubes. I think others do, too. The only exclusivity Grant has with tube distribution, I believe, is with the Shuguang Psvane 845.
You can find them cheaper than 600/pr, but beware. You may not be getting Grade A. If you go with Shuguang, buy from a North American retailer. Shuguang routinely exports their best tubes, and keep the lesser quality ones in China/Asia. So, if you go looking on ebay or something like that, and find a pair for 200 bucks, don't think for a second that you're getting a great deal from the guy in Shanghai.