It is a spectacular amp especially for the money. Rotel class D amp such as the RMB-1575 isn't that great. The RMB-1585 is far superior sounding and performing amp compared to the RMB-1575 (class D amp).
If you want to get something small compact in size (class D amp) I would highly recommend the Classe Sigma Amp5 five-channel amp, which is class D but sounding spectacular very smooth analog like sounding amp. Highs are smooth, fast, clean very transparent sounding amp. The Classe Sigma Amp5 retails for $5k. It is very compact in size and light weight. Classe uses its own proprietary class D design. Uses high current switching design with power factor correction (PFC) and it uses DSP to regulate the switch mode.
What is your preamp processor?
Classe also makes Sigma SSP av preamp processor to go with the Sigma Amp5 and will be a great match when paired together. Couple yrs ago I had a chance to hear the Classe Sigma SSP/Sigma Amp5 combo on the B&W CM10 S2 speaker system at my local dealer and they sounded fabulous together. I've heard it mainly in stereo when listening to stereo music but had a chance to try it out in surrounds for home theater (bluray movies). The Classe Sigma SSP preamp processor is optimized for stereo performance for stereo music playbacks or when used as a high end stereo preamp.
If you prioritize or value stereo music playbacks then the Classe Sigma SSP will be your perfect one box solution.
You won't need a separate dedicated high end stereo preamp with the Classe Sigma SSP in your setup.
Hope this helps.