Instrumentation amplifierYou may be looking for instrument amplifier, as used for amplifying musical instruments. This page is about the electronic device.
An instrumentation amplifier is a type of operational amplifier that has been specifically designed to have characteristics suitable for use in measurement and test equipment. These characteristics include very low d.c offset, low drift, low noise, very high open loop gain and very high input impedances. They are used where great accuracy and stability of a circuit both short and long term are required.