One of my biggest gear regrets is selling my studio preamp a little over a decade ago. Absolutely next level tones out of it.
Unfortunately the hassle dealing with racks, wiring, and power amps pushed me towards my Mark III head - but I credit the studio preamp with helping me discover a very strong preference for the Mesa Mark sound.
Remember when you could scoop one up for < $500? I found mine for $400 on a whim stopping in a GC in Boston back in 2007 or so. If I ever come across another for < $800 I’ll grab it.