@n80 my preamp also uses 6922 tubes and six of them so I am always on the lookout for a good value. I was turned onto these by someone in the forums here:
https://www.upscaleaudio.com/collections/vacuum-tubes/products/matsushita-national-pcc88-7dj8
It's a 7dj8 and from Upscale at $30 each a steal. I would call the sound very linear with excellent frequency extension and transparency. Not overly warm. And don't stress too much about tube rolling its fun and easy and preamp tubes will last you a good long while.
https://www.upscaleaudio.com/collections/vacuum-tubes/products/matsushita-national-pcc88-7dj8
It's a 7dj8 and from Upscale at $30 each a steal. I would call the sound very linear with excellent frequency extension and transparency. Not overly warm. And don't stress too much about tube rolling its fun and easy and preamp tubes will last you a good long while.