I received my 755 just the other day. It's heavy and I do not hear any hummm or buzzing noise at all. She is just as quiet as it can be. Just kind of heavy. When the power is on the Green button turns into kind of yellowish white... For the size see specs below....

See spec's below:

Model 755 Technical Specifications
Power output: 200 watts RMS x 5 (all channels driven simultaneously into 8 ohms from 20 Hz to 20 kHz with less than 0.05% total harmonic distortion). 300 watts RMS x 5 @ 4 ohms

S/N: 119 dB "A" weighted

Power Bandwidth: 5 Hz - over 100 kHz (+0/-3 dB)

Damping factor: 850 (10 Hz - 400 Hz)

Input sensitivity/Impedance: 1.43 volts for full output/28 k ohms

Crosstalk: Greater than -90 dB from 20 Hz to 20 KHz

Gain: Voltage gain of 28 dB

Slew rate: 50 Volts/microsecond

Remote Trigger voltage: 3 - 32 volts DC

Power requirements: 115 V 50-60 Hz

Power consumption: 1,800 watts (maximum)

Dimensions (W x H x D): 17.2 x 7.75 with feet x 18 (inches)

Weight: 78 (lbs)