Adcom GFA-555 MKII Stereo Amplifier in Box

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Here we have a legendary Adcom GFA-555II in the original box complete with all packing and manual. 

This unit has been well cared for and is in wonderful condition. There are plenty of 555's on the market but more were passed around from audiophile to audiophile and got beat up.  

The GFA-555 was quite the amp in the 90s and one of the top selling amps of all time.  It is super powerful yet comes in a fairly compact and light weight package making it easy for a single person to move around and put in place. 

While the Adcom company we knew and loved is no longer in business, prices on the top models seem to be going up and audiophiles on a budget rediscover the brand.  They are simple in design and use common parts so servicing them, if the need arrises should be an easy task performed by just about any technician. 

We tested this amp on our new test rig at its full rated power and it worked effortlessly without any signs of strain or noise.  

Inputs

100k Ω.

Two gold-plated, Teflon-insulted brass RCA jacks.

They are close enough together to make connection a breeze.

Gain

27 dB.

Input Sensitivity

1.75V for 200 W into 8 Ω.

130 mV for 1 W into 8 Ω.

Rated Power Output

200 watts per channel into 8 Ω from 20 - 20,000 Hz at less than 0.04% THD, both channels driven.

325 watts per channel into 4 Ω from 20 - 20,000 Hz at less than 0.04% THD, both channels driven (requires fan option to do this for any length of time).

600 watts into 8 Ω from 20 - 20,000 Hz at less than 0.04% THD, bridged mono (requires fan option to do this for any length of time).

850 watts into 4 Ω from 20 - 20,000 Hz at less than 0.09% THD, bridged mono (requires fan option to do this for any length of time).

 Dynamic Headroom

2.5 dB at 4 Ω.

Power Bandwidth

1.7 - 100,000 Hz at - 3 dB.

 Frequency Response

10 - 20,000 Hz +0, -0.25 dB at 1 W RMS into 8 Ω.

 Damping Factor

Not less than 800 from 20 - 20,000 Hz into 8 Ω.

 Noise

Not less than -110dB down from 200 watts into 8 Ω, A-weighted.

 Power Input

120 VAC 50-60 Hz.

72 VA idle.

1,500 VA maximum.

675 VA at 200 W into 8 Ω.

I measure 37.5 watts at idle, cold.

60 watts at idle, warm (0.73A).

92 Watts (1.09A) when delivering 1 watt per channel into 8 Ω.

845 watts when delivering 265 watts per channel into 8 Ω.

It draws zero power when turned off because it has a real power switch. It's not like modern equipment that never really turns off and consumes power and remains a fire hazard any time its plugged in. The GFA-555 II is completely disconnected when switched off.

 Size

Chassis: 6-3/4 x 17 x 12-3/16 inches (172 x 432 x 310 mm) HWD.

Overall: 7-1/4 x 17 x 12-3/16 inches (185 x 432 x 310 mm) HWD.

Weight

35 pounds (16 kg).

39 pounds (18 kg), packed.

 Quality

Made in USA.