The Adcom GFA-5500 is a two-channel power amplifier known for its 200 watts per channel (into 8 ohms) and its use of MOSFET output stages, offering a high-power, high-fidelity audio experience. 

Key Features and Specifications:

Power Output: 200 watts per channel (RMS) into 8 ohms. 
MOSFET Output Stages: Utilizes MOSFETs for audio amplification, known for their ability to amplify harmonics, musical texture, and extended bass with accuracy. 
Class A/B Operation: Employs a Class A/B design for efficient and powerful operation. 
Power Supply: Features a high-power toroidal transformer and high-capacitance storage for stable power delivery. 
Circuitry: Modular channel construction with short signal paths and accurate wiring placement. 
Damping Factor: High damping factor for improved speaker control and clear sound. 
Frequency Response: 10 Hz - 20 kHz (+0, -0.25 dB). 
THD: < 0.18%. 
Input Impedance: 49.9 kOhms. 
Dimensions: 7"H x 17"W x 15"D. 
Weight: 44 pounds.