Scarlett 18i20 Specifications:

Microphone Inputs:-

Frequency Response: 20Hz - 20kHz ± 0.1dB

Dynamic Range: 111dB (A-weighted)

THD+N: <0.0012% 

Noise EIN:-128dB (A-weighted)

Maximum Input Level: 9dBu (at minimum gain)

Gain Range: 56dB

Impedance: 3kΩ

Line Inputs:-

Frequency Response: 20Hz - 20kHz ± 0.1dB

Dynamic Range:110.5dB (A-weighted)

THD+N:<0.002%

Maximum Input Level:22dBu (at minimum gain)

Gain Range:56dB

Impedance: 60kΩ

Instrument Inputs:-

Frequency Response 20Hz - 20kHz ± 0.1dB

Dynamic Range110dB (A-weighted)

THD+N<0.03%

Maximum Input Level12.5dBu (at minimum gain)

Gain Range56dB

Impedance 1.5MΩ

Line/Monitor Outputs

Dynamic Range (Line Outputs):108dB

THD+N: <0.002%

Maximum Output Level (0 dBFS): 15.5dBu 

Impedance: 430Ω