Focusrite ISA Two by RevoltStudios
I bought this Focusrite ISA Two preamp as an entry into rack mount preamps aside from my large format console. I had heard some local albums done by a studio using mostly Focusrite ISA pres and very much loved the tone. Some describe the tone as soft or smooth, and I can see why. When pushing the inputs or outputs, you'll get a slightly compressed smoothness in the upper mids and lows. Your preference will determine if that is a good thing or not but for my tastes, I find the tone mixes easier and with less compression.
There aren't many fancy features to this preamp and thus, gives you quick, well balanced tones without wasted time knob twisting. The highpass is extremely useful and smooth with the only complaint being a lack of frequency labeling. The variable impedance works well but I have not needed any tone other than the "ISA110" setting. The inserts work great and don't seem to change the tone at all.
A hidden feature I've used is the line input next to the mic input. Want that ISA console tone? Try mixing at unity through the preamp. You may love it, you may hate it, but it's a great trick to have.
Mark this preamp down as a great option. Clean but with a hair of analog attitude. It's simple to use, has more gain than Warren Buffet, and can work in any situation. My only complaint? There's an input transformer, why not an output? Perhaps some day!