What Focusrite say:
Focusrite's ISA Two brings together a totally independent pair of classic ISA microphone preamps from the original ISA 110 module, combining the best of traditional solid-state electronics with the original input transformer specified by Rupert Neve – the Lundahl LL1538.
Each mic pre has the option of mic, line or the front-panel instrument input, with variable input impedance to ensure you are getting the best performance from the source. Up to 60dB of gain is available on the first four-position rotary and gain range switches, with a further +20dB of continuously variable trim, meaning a huge 80dB of gain is available should it be required. The high-pass filter features variable cut-off frequency between 16 and 420Hz. A pair of 8-segment LED meters show peak signal level in dBFS, while a rear-panel pot allows calibration to suit your A-D converters. Rear-panel insert points allow the use of inline processors such as compression.