Pre to meet 2021 goals

I'm looking for recommendations on what you would consider a "valuable" pre-amplifier. I want to evaluate different topologies of amplifiers, so if there is something that would be at home (gain, etc) going from a First Watt J2 to Decware Zen Triodes, to Atmosphere S-30 to vintage Conrad Johnson tube mono's, please advise. Maybe throw in a pair of Nagra Pyramids along the way! 

Most of my experience has been with integrated amplifiers. I've enjoyed integrateds  from Luxman (550, 590) McIntosh, Simaudio, Audio Research, Leben (300X, CS600), Mastersound, Almarro, etc. I listen to and tweak gear for 2-3 months before moving from impression to forming a real opinion, rarely owning something for less than a year or more, unless I find myself not pressing the power button.  

I have great sound from my Devore O/93, Leben CS600, Mojo Audio dac and power supplies, Roon Nucleus with Tidal and Qobuz. I'll be adding this pre alongside the Leben just to experiment and have fun with amps that peak my interest, or that friends own locally. I tend to gravitate towards tubes and the warm side of neutral.

I'm open to end game recommendations, but audio for me is an adventure where I enjoy variety. I have enough quality stable relationships in my life- electronics doesn't need to be one of them. If you want to share a story about how you settled on an amp or a topology please do.  If you want to criticize my methods go for it. If you need to rage about politics feel free.

Thanks!