I'm a tube newbie like you and it looks like you're getting great recommendations specific to your preamp. When I got the tube rolling itch, I contacted Aric at Aric Audio directly and he recommended a specific set of tube brands and models; rectifier, voltage regulators, and 12ax7 signals, and I swapped them one at a time over a month period just to gauge the improvement. Collectively, they took the preamp to an entirely new/better level. His recommendation was based on his own personal experience rolling many different brands/models in the same unit he uses regularly in his own system. So sometimes asking the designer may be a good approach. Mine came with JJ 12ax7 signal tubes and apparently the Electro Harmonix Gold pins work best in this particular model. Total cost was $85 for 5 tubes. By the way, in my case, the overall difference after the swap was not subtle or just a matter of taste, etc. It just made the music sound better. I asked him why doesn't he sell them with these tubes and his response was I was the first person who contacted him for tube suggestions and secondly most people have a favorite brand/model in mind and just go ahead and roll tubes regardless of what comes with the unit so why put more expensive tubes in. By the way, he also gave me some recommendations for upgrading a small number of the capacitors to Audyn Copper to make it sound "crazy" good. That's my next plan.
Good luck and enjoy the music.
Good luck and enjoy the music.