A hearing instrument comprising: a microphone (M M) comprising a microphone transducer element mounted in a microphone housing wherein the microphone transducer element produces a transducer signal in response to receipt of sound, a microphone amplification circuit configured to generate an amplified microphone signal from the transducer signal, a control and processing circuit coupled to the microphone amplification circuit for receipt and processing of the amplified microphone signal according to a hearing loss of a user; the microphone amplification circuit having a power supply port coupled to a switchable power supply, the switchable power supply is configured to selectively connect a first power supply voltage (V DDL), having a first DC voltage level, or a second power supply voltage (V DDH), having a second DC voltage level, to the power supply port of the microphone amplification circuit; where the second DC voltage level is higher than the first DC voltage level, a level detector configured to detect a level of the amplified microphone signal and connect the first or the second power supply voltage (V DDL, V DDH) to the power supply port based on the detected level of the amplified microphone signal, wherein the microphone amplification circuit comprises: a first preamplifier coupled directly to the transducer signal of the microphone transducer element and supplied with power from the first power supply voltage (V DDH), or a third power supply voltage with a third DC voltage level lower than the second DC voltage level, a second preamplifier comprising a signal input port coupled to a signal output port of the first preamplifier and a power supply port coupled to the switchable power supply. a microphone (M M) comprising a microphone transducer element mounted in a microphone housing wherein the microphone transducer element produces a transducer signal in response to receipt of sound, a microphone amplification circuit configured to generate an amplified microphone signal from the transducer signal, a control and processing circuit coupled to the microphone amplification circuit for receipt and processing of the amplified microphone signal according to a hearing loss of a user; the microphone amplification circuit having a power supply port coupled to a switchable power supply, the switchable power supply is configured to selectively connect a first power supply voltage (V DDL), having a first DC voltage level, or a second power supply voltage (V DDH), having a second DC voltage level, to the power supply port of the microphone amplification circuit; where the second DC voltage level is higher than the first DC voltage level, a level detector configured to detect a level of the amplified microphone signal and connect the first or the second power supply voltage (V DDL, V DDH) to the power supply port based on the detected level of the amplified microphone signal, wherein the microphone amplification circuit comprises: a first preamplifier coupled directly to the transducer signal of the microphone transducer element and supplied with power from the first power supply voltage (V DDH), or a third power supply voltage with a third DC voltage level lower than the second DC voltage level, a second preamplifier comprising a signal input port coupled to a signal output port of the first preamplifier and a power supply port coupled to the switchable power supply. a first preamplifier coupled directly to the transducer signal of the microphone transducer element and supplied with power from the first power supply voltage (V DDH), or a third power supply voltage with a third DC voltage level lower than the second DC voltage level, a second preamplifier comprising a signal input port coupled to a signal output port of the first preamplifier and a power supply port coupled to the switchable power supply.