what nos tubes for mystere ca21 preamp

suggestions for nos tubes for mystere ca21 preamp
It would help if you mentioned what type tubes it uses.
Tung-Sol NOS 6SN7GT
Mullard NOS 5AR4

I bought mine from Andy at Vintage Tube Services. Great service and excellent tube quality. This combination seems to work best for me in my CA21.
Was that the Round Plate Black glass Tung Sol. They would improve jut abou anything they're put in.
thanks wescoman purchased same tubes from andy at vintage tube services.will see how they sound.
I have the Mystere CA-21 preamp and use the standard tubes it came with and am wondering how the NOS tubes compare. I love the music this preamp makes already. Thanks!