from Marantz Esotec MA-5 to hometheatre

I have a stereo equipment that I would like to upgrade to home theatre.
Amplifiers are: PRE Marantz Sc-8 and 2 mono Marantz Esotec MA-5 (150W) bought in 1983.
I would like to keep the mono amplifiers as I think in terms of quality stereo sound are better than any home theatre ampli (does anybody agree ?).
I am oriented to buy a Yamaha RXV 1400 or 2400 or Denon AVR 3805 all with pre-out connections and automatic parametric equalizer and drive the two front speakers with my Marantz MA-5. What do you think about my idea; would it work (sound quality) ?
has anybody ever made similar experience ?
Before extended my stereo equipment to hometheatre I would be sure of the choice to be done.
thanks mario