If you are not using the phono stage it will not make a difference. Save some money and ignore those tubes.
I have a C2300 and highly recommend Amprex Medical Grade 12 ax7s, they are extremely pricey but ultra quiet, rugged and will last for years. I’ve had mine in for 4 years and my preamp is on literally 6-7 hours a day (as a passthru in my home theater system) and it sounds wonderful. I only use the medical tubes in the MC Phono stage and the Aux stage because I don’t have a MM TT. This is a great preamp that is smooth and sophisticated without the DAC on board, that is preferable to purists like me. I hope you continue to enjoy your C2300!
I am an original owner of the C2200, which is similar to the C2300, and I have used various tubes over the years. The C2200 uses four 12AX7 and four 12AT7 tubes. I don't use the phono stage.
I just recently contacted Brent Jessee (who is well respected on these forums) asking his advice for tubes for this preamp. He was very prompt in his reply to my email. I will be ordering from him this week.
I suggest that you email him with your question. His website is loaded with information as well: https://www.audiotubes.com