Hey Ait. Congrats on your preamp choice sir,and it's well worth the wait. As others have suggested: run it in for a few hundred hours before rolling tubes. Most nos 6sn7's from different manufacturers[and there are many] will have a flavour... the RCA grey glass is a good one but do roll out the sovtek rectifier first. An old nos Mullard GZ-34 is far superior[sonically] and will last for many years to come.
