We report on a two-stage system consisting of a dc SQUID magnetometer inductively coupled to an amplifying second stage realized by a SQIF. The SQIF is a series or parallel connection of dc SQUIDs with various inductances, which facilitates a unique global minimum in the voltage-flux characteristic and ensures a stable operating point, a high voltage swing and a large transfer function of the system. The noise of the amplified signal is dominated by the input stage and its voltage swing exceeds 1 mV which reduces the demands on the readout electronics. A part of the current of the SQIF can optionally be fed back to the feedback coil of the first stage SQUID, so that an on-chip linearization of the voltage-flux characteristic is realised. The short feedback path enables a substantially higher bandwidth compared to a flux-locked loop using a room temperature amplifier. From experimental results it can be expected that this setup is capable of measuring magnetic fields with a high slew rate and dynamic range.