Your current Integra DTM-5.3 is a stereo receiver with A/B speaker capability, not actually four channel. So, a stereo integrated amp with A/B speaker will function exactly the same.
In addition to the Marantz, take a look at the Harman Kardon HK 990, and
the NAD C 375BEE with optional phono stage (PP375).
In addition to the Marantz, take a look at the Harman Kardon HK 990, and
the NAD C 375BEE with optional phono stage (PP375).