I don't think its the speakers or the amp that is making you second guess the sound your getting from your system.
It's using a Marantz Pre-Pro as your pre-amp thats your problem as this is the weak link. It was designed for multi-channel sound decoding and processing. The 2 channel pre-amp section in your Marantz, even in pure direct mode, is merely an afterthought by the manufacturer. You said your moving away from multi-channel and going 2 channel only, right? So get a component designed to do 2 channel stereo - get a true stereo pre-amp!
Good luck brother.
It's using a Marantz Pre-Pro as your pre-amp thats your problem as this is the weak link. It was designed for multi-channel sound decoding and processing. The 2 channel pre-amp section in your Marantz, even in pure direct mode, is merely an afterthought by the manufacturer. You said your moving away from multi-channel and going 2 channel only, right? So get a component designed to do 2 channel stereo - get a true stereo pre-amp!
Good luck brother.