hifi engine

connecting two marantz 190 amps together

i want to know how to use my two marantz 1090's together, one as a pre-amp and one as the main amp. i bought new, in 1978 a full marantz audio system, with a 1090 amp, a 2110 tuner and HD770 speakers. i acquired another 1090. and want to be able to use them both.
any help?