Adcom GFA 555
The Original Nelson Pass design version ( the  555 II was an update which he was NOT involved with)
SOLD!!!   /b]within the contiguous USA
*local pick up in MA also available 
Output Power:
200W into 8 ohms (23dBW); 
325W into 4 ohms (22.1dBW),
600w into 8ohms Bridged Mono
850w into 4 ohms Bridged Mono
all continuous power, 20Hz-20kHz, with 0.09% (0.25% bridged) THD.
Input impedance: 22k ohms. Sensitivity: 130mV.
Dimensions: 
17" W by 7" H by 11.5" D. 
Weight: 
34 lbs.