interfaces have a variety of hardware functions operated from Focusrite Control, rather than by physical controls on the unit itself.
The Input Settings page gives you access to these functions. The page for the Clarett⁺ 8Pre looks like this:
If you have a different Clarett⁺ model, most of the functionality will be the same, but fewer switches may be visible because your interface has fewer channels.
Each input channel of your Clarett⁺ interface has a switchable AIR function; this analogue circuitry emulates the classic Focusrite ISA110 preamp. See your Clarett⁺ User Guide for more details.
AIR can be switched in and out of circuit independently for each channel by clicking the AIR buttons. The LEDs on the unit’s front panel will also confirm AIR has been selected for each channel.
Inputs 1-2 on all Clarett⁺ interfaces accept electric instruments directly. Selecting INST for these channels unbalances the input and alters the gain and impedance to optimise the pre-amplifier for a high-impedance source like an electric guitar.
Selection of INST mode is confirmed by a red LED on the unit’s front panel.
The alternative switch position for these channels is LINE; in this mode, the inputs are suitable for a standard balanced line level signal.
All the channels on your interface are able to accept dynamic or condenser microphones. The Combo-type connectors sense either an XLR plug or a jack plug, and reconfigure the pre-amplifier for mic or line operation automatically. The channels which additionally have the INST function use the same connector.