That being said, I highly recommend the Classe Sigma Amp5. The Sigma series is Classe's entry level series. It is a step up sonically from the big Rotel RMB-1585.
But the RMB-1585 is a great amp too especially considering its asking price and was built like a tank. Actually the Rotel RMB-1585 runs cool. Comes with 2 fans placed toward the back panel and the fans is barely inaudible. The internal heat management is superb with this amp. No matter how hard you drive it the amp will never get warm or hot.
The sound is very fulsome, fluid very musical very smooth and has full midrange bloom and has a bottom end grunt you desire but I found this amp lacking a bit in extracting all musical nuances and information, details, transparency and resolution in comparison to the Classe Sigma Amp5.
The tonality is leaned towards the warm side of neutral. The RMB-1585 has a level of great warmth that people desire especially for listening to music.
The Classe Sigma Amp5 however sounded more resolved, cleaner, faster with much better details, transparency than the Rotel RMB-1585. The Classe Sigma is a lot more revealing sounding amp without sounding harsh or bright and the Classe Sigma Amp5 excels in extracting all musical nuances details and information and with greater drive, rhythm, pace, timing and speed than the Rotel RMB-1585. It sounded clean, fast with more solid accurate imaging and greater soundstage than the Rotel. The imaging and soundstage is vast with 3D like. Overall the music or movies sounded and felt more alive with the Classe. Everything is popped with the Classe whereas with the Rotel as if there's haze blanketed the soundscape and things become more obscured whereas with the Classe everything becomes more solid and obvious.
But the Classe Sigma Amp5 is a very revealing amp and will reveal the weaknesses of the source such as bad recordings, and qualities of your upstream electronics eg preamp/processor, source component (player), DAC, etc. It also reveals the weaknesses of your cables and speakers qualities. Make sure you get the good quality and the right cablings (speaker cables, interconnects, power cables, etc). And I wouldn't recommend using your Pioneer receiver as your preamp processor as the Classe Sigma Amp5 isn't forgiving of the source and quality of upstream electronics eg preamp, processor, etc. As your budget opens up more later down the road I would recommend that you upgrade your preamp processor and source component (player, etc).