The John Hardy Company M-1 Mic Preamp Two-Channel by spiral
Clean. Clean. Clean. The Hardy M1 is the gold-standard mic preamp for a few very good reasons. The first reason is that it takes any mic and makes it louder with very little (if any at all) coloration. It does this with an incredibly low noise floor which makes this a no-brainer for gain-hungry ribbon mics and delicate acoustic music. If you have passive ribbons and love them on acoustic guitar the M1 is up to the task. The M1 comes with a transformer option but i didn't feel it added "huge iron" to the sound. Another reason you will find this in the racks of professionals is the build quality. Looking inside the M1 reveals an immaculately laid-out and built piece of machinery. I've seen John's "factory" (ie. his house). He builds each unit by hand (and wave solder machine) and the craftsmanship shows. Physically the unit is heavy and every inch is robust and thought out, even down to the ceramic knob pointers.
If you are looking for vintage coloration or big huge sound this is not the preamp for you but if you need pristine amplification with low noise floor, a piece of gear that will last forever, and a ton of gain, the M1 is a requirement.