The MZ3 from Linear Tube Audio can be read about;

https://6moons.com/audioreview_articles/lta4/

https://www.enjoythemusic.com/magazine/equipment/0820/LTA_MZ3_Vacuum_Tube_Preamplifier_Review.htm

https://twitteringmachines.com/review-linear-tube-audio-mz3/

https://www.lineartubeaudio.com/

And the head-fi thread:
https://www.head-fi.org/threads/microzotl-3-by-linear-tube-audio-true-high-end-audio.895908/

I love it and I’m selling to move up to the LTA Z40+ integrated. All original packing materials and manual. I took delivery in late October last year and the condition is immaculate. It been used to drive Focal Utopia 2022 and Radiance, as well as acting as a preamp driving a Pass Labs XA25

PM with any questions at all. I’m flexible and helpful!