Fans are a potential source of noise, but if your using a pro amp in a consumer setting and will not be overdriving them, you could disable the fan and it still function reliably. As for noise floor and sound quality, my favorite amp was always Crown, but then below the Crown, I would rate the QSC and AB amps next followed by Carver then Peavy, just to name a few that I have used in pro-sound reinforcement days. You would likely be well served by the Crown or QSC as long as you get the ones that are stereo 4ohms. Bridging or running 2ohm loads will increase the THD and your noise level accordingly. I have had 30,000 watt arrays that were whisper quiet with the Crown MacroTechs that we used. To respond to your point about output transistors, I just remembered another point, there are various types of amplifier IC's and generally, the ones like in the Outlaw are the small plastic encassed units. But that made me remeber the type in the pro-amps are the large metal encassed units. Accordingly, don't compare number of IC's in these because they are two different types.