Marantz PM8006 integrated amp as preamp

I have a Marantz PM8006 integrated amp and KEF LS50 speakers.  If I use the Marantz integrated amp as a preamp and then add a decent amplifier will I improve the sound quality?  My other equipment is a denafrips aries ii DAC, Cambridge Audio CXC CD transport, Bluesound node 2i, and dual REL T/7i subwoofers.  I'm considering the Parasound Halo A 21+.