tube character with pre-amp

As a new and excited tube pre-amp owner I wonder if a few can give ideas of tubes that can one day be explored in my Sonic Frontiers, I know little to nothing of what tubes have what sonic character so I am asking for opinions, I will say I am sorry if this has been hashed out to death here. I may also want to add that I am using Innersound Eros Electrostat Hybrids and like the sound, at increased levels the highs can start to fatigue although I am not sure if this is blamed by my Rotel Pre, my room or both and then some.....thanks