I recently decided it was time to upgrade from the built in preamps in my Focusrite Sapphire to a 'real' external preamp. My budget was about 600 EUR. Afer a LOT of online research, I narrowed my options down to 6 preamps, in roughly the same price range. The preamps were:
ART Pro MPA II
Warm Audio TB12 Tone Beast
Black Lion Audio B173 Preamp
FMR Audio RNP 8380
Warm Audio WA73
Focusrite ISA One Analog
As I will be using the preamp mostly for vocals and bass, I tested both those signals.
I plugged my Ibanez 600 in passive mode into my BSS DI, into the preamp. For vocals, I hooked up my SM7B straight into the preamp, into Logic X. The results:
The Focusrite ISA One is the biggest preamp out of the bunch, and built like a tank. Sound wise, it is the most clear pre out of the six. Compared to the built in preamps in the Sapphire, there is definitely more clean gain, with the base character of the tone remaining mostly unchanged. The tone shaping options are more than decent, and there is a lot of I/O. In the end, the ISA One didn't make the cut because it felt too clean, and not big enough of a palpatable difference with the Saphhire.