Congratulations on your new amp! The V3M is one of my all-time favorites. I hope you really enjoy it!
The most critical tube for noise is the very first preamp stage (farthest from the power tubes). If you want a broader resolution on your channel gains try using an ultra low-noise 12AX7 with moderate (rather than super high) gain. I always have great luck with an Electro Harmonix 12AX7-EH in there (in fact in most of the preamp tube positions). There is also a very nice quiet smooth Mullard 12AX7 reissue that New Sensor offers. The amp has enough gain for days with even a medium gain tube, and by using lower gain preamp tubes you get more control of the clean-to-distortion range of the gain controls. Also make sure to explore the channel voicing switches (Ch 3 has its own special ones btw) and the EQX switches. If you didn't get a manual you can download it from Carvin Audio's support page.
Carvin Amplifiers endorser since 2010:
V3, V3M, MB12, S600B, PM15, FX2, UX100BP, PM900, Carvin CT424