Yamaha PX3 Amp.\n\nSettings:\n\n1. Full Range Mode (20Hz-20kHz): 26dB and 32dB Gain, Gain set at 100% (Max, 0dB). EQ off. This was for Front Left and Right speakers.\n\n2. Subwoofer Mode (20Hz-150Hz): 26dB and 32dB Gain, Gain set at 100%. HPF set to 20Hz (adjustable increment of 0.5-0.6 Hz). LPF set to 150Hz (adjustable increment of 1 Hz). EQ off. This was powering a total of 6 subs- four Velodyne 12” subs and two RBH 1010 subs (dual 10”).\n\nQuestions.\n\n1. Does it have hiss noise at tweeter? Yes, slight hiss noise from less than 6 inches away. Cannot hear any hiss noise farther than 6 inches away. The level of hiss seems quieter than the Crown XLS Gen2 that I played with a few months ago. Both 26dB and 32dB Gain had the same amount of hiss.\n\nThe ATI AT2005 and Yamaha MX-A5000 are dead silent.\n\n2. Does the fan come on? 100% of the time. The noise level is very low similar to a regular 80mm PC fan. I could not hear the fan from 2 FT away. As seen in the pics, the 2 fans are in front and look just like a regular 3-pin PC fan. So if they ever fail, you unscrew the 2 fans and replace them just like in a PC. The fan pulls air in from front to rear. The vent holes are only in front and rear. No vent holes on bottom or top. Makes it perfect for stacking amps.\n\n3. The amp ships without the Rack Mount Ears attached to amp (they are included in box) , unlike all the other Pro amps I’ve seen. Thank you Yamaha!\n\n4. As for sound quality, the PX3 amp sounded great for both full range speakers (RBH SX-T2\/R x 2) and for subwoofers (RBH SX-1010 x 2 and Velodyne SC600 x 4).\n\n5. Removing the top cover requires removing 3 black screws on left side, 3 black screws on right side, 3 black screws on rear, and 4 silver screws on front top.