Did you listen to the Speaker before the purchase? What were powering it? Same also for the Marantz, did you test and what were the connected speakers and stuff used to test?

Maybe now it is time to see what went wrong during the audition and why now you cannot get satisfaction?

Lastly, Astro really not the best medium to test... in fact one of the worse....

Curious on the Astro, you patch the audio to TV and from TV back to Marantz? Or from Astro decoder to Marantz then onwards? Anyway, Astro not the best to test, just curious only on the hook-up.
Normally Marantz are not known to be "Bassy" and it tend to be warm sounding, not bright sounding.
Lastly, the Yamaha you compared against are a more powerful unit against the Marantz and Yamaha are more toward neutral bright sounding. Not forgetting, Yamaha have quite a nice set of bell and whistle.