The Alice MHB Input Extender is a two-channel microphone input accessory for the Tieline ViA codec. It provides two additional analog mic inputs and left/right headphone monitoring via captive audio leads. The unit is powered by an internal 9 V PP9 battery or a 230 V AC to 12 V DC mains adaptor. It measures 145 × 145 × 60 mm and weighs about 1.5 kg. Frequency response is 20 Hz to 20 kHz ±0.2 dB with noise around -100 dB and gain up to 20 dB; maximum input level is +28 dBu and output about +26 dBu into 5 kΩ.