Stout, Silent, Worm Performer,

Distortion LED indicators hard to see from a distance

Good performer works hard without missing a beat. Running front mains KEF 104.2, have a pair of NAD 2200s for center and rears, with a Sony 30ES HT Receiver. Very uniformed and killer system. This is a warm sounding amp. I would recommend either the GFA-555 or NAD 2000 to supplement any home theater system. Good, clean and strong power is hard to find, for the money can not be beat!

Similar Products Used:

NAD 2200, Yamaha M-85

Absolutely reliable and still compares reasonably well against others

Slight lack of "air" and base control

I bought an early GFA-555 and left it on in my system for nearly twelve years. (I don't turn off solid state amps) Two years ago I put it into a closet and have since been using considerably more expensive equipment. Three days ago, my current amp, a Coda, blew the left channel (bang - loud four or five second whistle - then smoke). I decided to get out the Adcom to see it's still working while the Coda's away for repairs.

After carefully cleaning all the connectors, I let it warm up overnight and then started to listen. There is a slight loss refinement, base control, and a somewhat different presentation compared to the Coda. However, I find the sound to be full, slightly forward, and generally quite pleasant. In many ways, it sounds fine. In fact, I realize that I could probably live with this thing again and not feel sorry for myself.

If you're looking for some used equipment for a low budget or second system and can find a reasonably priced GFA-555, I'd heartily recommend it.

Similar Products Used:

Several solid state amps and one tube amp.

This is a reliable amplifer and is truly rated at 200 watts per channer rms.

Sound quality is not as good as high end gear on speakers with complex crossover networks.

I have been useig the Adcom 555 to push a pair of JBL 2012H 10" midbass to midrange transducers. These speakers are ran straight from an electronic crossover set between 160hz and 1.6K hz. I play the system at high levels.
I have used this amp for several years now. I believe this amp to have great power handeling, even when driven for long periods of time.
I did use the amp breifly to push a pair of Infinity Kappa 8s and didn't find it to perform as well, compaired to my AR or Classe amp, but then the Adcom did not cost as much either.
I would say that this amp is a true workhorse; it reminds me of the older Macs, perhaps not as smooth and sweet sounding, but just as reliable.
I would recommend this amp to anyone looking for a good strong powerful amp. It would make a great addition to a receiver for pushing the low end on large or inefficient main speakers. Something to consider if one wants better sound and still have a home theater system, as they can be purchased on ebay at a modest cost ( just watch the shipping, as this amp is heavy), the 555II is of the same quality.

Similar Products Used:

High end seprates, from older Macs to modern class A amplifers.

Powerful, Transparent, Dynamic, Smooth, Detailed, Wide, Open

None, especially for the cost

My beloved Bryston 7B-ST's were recently replaced after a natural disaster by a pair of Adcom 555's of which I am using in bridged mode. It was really all I could afford at the time. I have been using Magnepans and Apogees for about the last 7-8 years. I recently had a pair of Magnepan 2.7's then more recently my current 3.5's that I had been running with the Bryston's. I always thought they were a great amp but a bit edgy. Strange but true, every weakness I perceived from the Bryston was gone with the Adcom’s. They are powerful, transparent, dynamic, detailed, wide, open and much smoother than the Bryston’s. I truly think they're a great product at any price. Now that I'm back on my feet I'm in a quandary. I love the sound of these amps but can afford better. I guess I'll keep them for a while and enjoy.

Similar Products Used:

Carver TFM-35X, Bryston 7B-ST's

Huge amounts of power in stereo. Really handles musical
peaks with authority. Distortion led make driving speakers
to max spl's easy to do without damaging anything. When
used in bridged mode, subwoofers beware.

This is flat out one of the best values in the market. You can easily find one of these used for under $400. At a conservatively rated 200 watts per channel in stereo, this amp has plenty of juice to drive almost any pair of speakers. I have run this amp with Klipsch, Infinity SM, and other high efficiency speakers and it really smooths out the sound, where other amps can make them sound harsh and tinny. As other reviews have stated, this amp is bulletproof. I have run four pairs of speakers and a subwoofer off this amp at once and it can play all day. The distortion alert leds are a great asset to anyone interested in pushing their equipment to the edge, without breaking it. I am currently running this amp in bridged mode, which turns this powerful amp into a wrecking ball. My heavy-duty, professional 18" subwoofer gives out well before the distortion lights flicker.
In conclusion, if you're a snooty audiophile or someone who's paycheck has more than three zeros, then you might want to look elsewhere. However, if you're looking for a sweet sounding amp that won't make you refinance your house, this is it. Also, if your desire for extreme sound pressure levels borders on sado-masochistic, but you make less money than an ice cream truck in alaska, this amp proves that there's hope for you yet.

Similar Products Used:

Hafler DH100, DH500

I've had one of these for over 10 years now, driving Vandersteen 2Cs (bought about the same time) through Kimber (bi-wired), and an ADCOM GFP-555 preamp. I've never heard a setup since in the sub $10,000 range that does a better job. Experience has shown that the amp needs to be warmed up about 2-3 hours to get the full effect however - the longer you leave it on, the better it sounds. When I bought the 555, it was rated one of the best sounding 2 or 3 amps under $5K by Audiophile, Stereophile, etc. (at the time, it was right around $1000). I haven't heard the newer models from ADCOM since they went more "mainstream" - I guess they tried to improve on it, but...if it works...

Power and bass control.

Distorted highs.

I am a little disapointed after owning a 545. It is definitely more powerfull. I think that it would make a great amp for the bottom of a bi amped system but I have just replaced it because it was distorted on the high end. The 545 has an ambience that makes you want to listem more. The 555 shares only some of the sonic characteristics. It's obvious that it uses bipolar transistors like the 545 and the basss has a similar sound but is amplified more. Other than that the 545 wiped up with the 555. On pink floyd the ambience was ecapsulating with the 545 but the 555 was just loud. I may have goten a dud but this one didn't impress me. Use it to run subs but not tweeters.

Similar Products Used:

Adcom 545, B&K 3140, ATI 1506, Other Higher end stuff.

Best price to performance ratio in the business. Easy to monobridge.

None

If you look at my list of product experience, you'll quickly gather that I am "old school hifi". I think that simplicity is the ultimate sophistication. Therefore I always seek the maximum enjoyment for the minimum amount of equipment.
With that in mind, I located and purchased an Adcom GFA 555 for under $400 locally.
Previously, I had been using a Hafler DH100A Preamp and DH 220A amplifier. Currently I have the Adcom GTP450 preamp running through the GFA 555 amplifier, down a set of Monster Cables and into a pair of B&W DM602 series II loudspeakers. It sounds very good, but I know it could be better. The preamp is the limiting factor here, not the amp.
I found the earlier review from Joseph of Louisville to be very interesting. He never states what brand of preamp he uses. The Adcom is very dependant on a good preamp. Before I sold my Hafler preamp, I used it with the Adcom amp. Incredible soundstage, absolutely indescribable. Using the Sheffield Track CD, I could close my eyes and focus exactly on the positions of each piece of Jim Keltner's drum kit. With the Adcom GTP450 preamp, I lost all that. Some of it returned when I added the B&W speakers, but until I find a nice simple preamp to replace this integrated thing, it'll never be right. I recommend using a Lazarus (if you can find one) or Hafler preamp with the Adcom GFA555. You won't regret it.

Similar Products Used:

Hafler DH220A, Nakamichi PA1, Perreaux 2150B, Proton D1200, Sony STR6800SD, NAD

Absurd, clean power, Cheap Amp but sounds World Class

I like it very much. Depends on your taste

My First powerful amp. I Was using the B&K av5000 at 100 watt before.. the B&K is laid back...I Added the ADcom just to see if the sound will change ..couple with my AudioResearch LS8, CAL CL-10 cd player, B&W 602 ..I like the sound alot. The Clarity and power is great ..make the speakers sing with ease and the soundstage deepen. The Adcom is brighter but because of most of my gear is decent, the Sound is not Harsh. It is more exciting..than the B&K. Certainly clearer ..What a JOY. I am thinking about getting another one to bridge it to 600 watt/channel. I will be using it with my NHT 2.5i. But that's another story for another day. I highly Recomend the amp. It's Cheap and powerful..for the money..a great Value.

Similar Products Used:

B&K Av5000

Lots of talk about Adcom amps, thought I'd better add something on the one I've been running for about 4 years now: a GFA-555, purchased used at the time for $500. The version I have is NOT a Mark II, however it looks very similar (black w/ signature Adcom horizontal grooves). Apparently there is a predecessor to my black GFA-555 that confuses people into calling mine a Mark II, which it is not. Anyway, 200 wpc, bridgeable. Running it w/ a pair of floor standing 3-way speakers (the G-3s from mail order Audio Concepts Inc., known for their somewhat laid back presentation), w/ both tubed and ss preamps, this amp has never let me down. It has, however, allowed me to hear differences in some front end equipment, positive and negative. For me this amp has sounded best w/ a conrad-johnson PV-8 at the front....very very very detailed and fluid. It has been a workhorse and from all I've read I think was the first and only Adcom amp to live up to all the marketing hype. I can't speak for it's little brothers (535, 545).