Adcom GFA-555MKII Amplifiers

4.29/5 (34 Reviews) MSRP : $900.00


Product Description



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Reviews 1 - 5 (34 Reviews Total) | Next 15

User Reviews

Overall Rating:5
Value Rating:5
Submitted by eherdian a Audio Enthusiast

Date Reviewed: August 25, 2011

Bottom Line:   
I've been using this adcom for 5-6 years, I bought it used for USD $ 350
If you had been heard several "high end" power, you will know that your adcom have many weakneses, it sound harsh, have punchy bass but not low enough, not really sweet vocal etc.
So I decided to make several modification and upgrade the component.
I added SCR / Solen (from 22 uF to 68 uF) bypassing on supply capacitor, replace critical standard capacitor with blackgate F caps, replace feedback resistor with audionote tantalum resistor, bypassing input cap with dynamicaps caps, replacing standard KOA wirewound resistor with the better ones, adding capacitor smoothing for input electricity.

The result is very satisfying, the adcom could beat BRYSTON 4ST (yeah you;re not misread....hahaha)
sounds very smooth from top to bottom, still dynamic, still punchy with deeper bass, and detailed

I'm using magneplanar 1.6 and fostex 206 modified with scanspeak 6600 tweeter
and the loudspeaker cable is the beautiful sounding cardas golden hexlink 5

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Used product for:   More than 1 year

Duration Product Used:   Audio Enthusiast

Product model year:   Pre 1995



Overall Rating:5
Value Rating:5
Submitted by ces4x4 a AudioPhile

Date Reviewed: June 29, 2011

Bottom Line:   
Want to make this amp really sing, replace the driver stage caps with Nichicon Muse Fine Gold caps. I had my service tech do it for a mere $175. Let the amp then burn in for at least 50 hours sit back and be in awe!! Individual instrument placement and definition is unprecedented and I have owed many amps over the years. I have yet to experience any listening fatigue since the upgrade. Low level listening, high level listening, it all sounds great. Bass is airy, no sense of boom, mid-range is so detailed now I can hear every word spoken, guitar riffs are just eye opening. If you are not a believer that caps make a difference modify this gem and you will become a believer. My tech wasn't a believer until I had him modify this 555II, he is now!! He currently has one of my Rotel amps that I am having him replace the caps in, looking forward to hearing how that turns out. Before the mod the Rotel bested the Adcom, after the mod the Adcom smoked the Rotel. Curious what the caps will do for the Rotel. The Rotel uses Black Gates too!! After hearing the Nichicons in the Adcom the black gates are being pulled. So I looked in my Arcam CD73 to see what kind of caps were in it and low and behold I find Nichicon Muse Fine Golds!! Wonder what my McIntosh C220 preamp has in it?

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Used product for:   More than 1 year

Duration Product Used:   AudioPhile

Product model year:   Pre 1995



Overall Rating:5
Value Rating:5
Submitted by couldbee a Audio Enthusiast

Date Reviewed: November 21, 2009

Bottom Line:   
What a gem! This thing has more power than a demented dictator. I purchased this unit today on Craigs List for $250 in mint condition! I jumped on it based on the reviews that I read here on Audio Review and Stereophile. It just churns out the music with fantastic airy highs and thunderous bass. Placement and separation of the instruments are phenomenal! I am awe struck over the soundstage that it reproduces. I lost my job a couple of years ago and had to give up my Audio Research, Krell, and Rowland equipment! I reduced myself to Kenwood and Sony. Audio suicide! I have been trying to economically put together a system that would at least satisfy my ears. When I came across the Adcom my mission was completed. If I were to take the blindfold test I would not be able to tell it from my Krell or Rowland. Oddly enough it sounds like the two have combined! It has the same type of Krell bass slam and the finesse of the Rowland 5. Now I can sit down and actually enjoy the music rather than criticize it and complain about what I need! I would love to find another one and run them as mono amps. What a treat for the auditory canal that would be. I highly recommend this unit to whoever is considering listening to it. It will not disappoint, just delight! I have had over 100 different combinations in the past trying to achieve a certain sound that I have in my head. Mission accomplished. The price is a spit in the ocean compared to the past amps that I have owned. My hat goes off to you Adcom.

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Used product for:   Less than 1 month

Duration Product Used:   Audio Enthusiast

Product model year:   Pre 1995



Overall Rating:5
Value Rating:5
Submitted by gyusher a AudioPhile

Date Reviewed: December 27, 2003

Bottom Line:   
I buy and sell classic audio gear on eBay among other places. This means that I am constantly changing speakers, PreAmps etc. I need a good powerful amp of signifacant quality, one versatile enough to play any speaker on the planet. I owned several of Adcom's earlier amps including the GFA-1 and 1A. I gought the first series Definitive Technology BP-20s when they first hit the market so I bought a 555 Adcom to power them and was never disapointed. Always plenty of power to drive the BP-20s to wickedly loud levels cleanly and effortlessly.
As time passed and after continuous upgrades into a full blown HT setup I found I longed for the good stereo sound again, simple and uncluttered in my office/computer room. I remembered my experience with the 555 so when my friend was selling mint 555IIs I bought one. I remembered my old JBL L-112s and found a pair of them. Next I needed a decent PreAmp when along came a Sony TA-E77ESD, now we are talking pushing a classic pair of JBLs with enough power to light a small town everything came back. The JBLs were a bit dated and I wanted a more hi-res speaker so I put a pair of NHT Super Ones on this 555II and WOW! those who think the NHTs are a little thin havnt heard them behind a 555II. After dozens of different speakers I now use Sonys SSTX7S a overseas MTM model with glass cones and I am here to tell you that the sound is extraordinary, comming is a hand built pair of 7in 2ways that my friend is building for me and I expect this 555II to sing with these as well.
I read every review written here about this great amp. I hear things like grainyness etc. when I hear nothing but clean, clear music out of everything I put on it. Of course there are differences between different speakers but I never thought for a moment that any thing other than good was comming from my 555II.
I see people comparing this 500 dollar amp to multi thoasand dollar amps, somehow the Adcom can't cut it when comparing it to a amp costing ten times the money, call it mid-fi, low-fi or what you will. I call it great. A great amp at a great price period.

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Used product for:   More than 1 year

Duration Product Used:   AudioPhile

Product model year:   Pre 1995

Price Paid:    $500.00

Purchased At:   Friend / Amplifier t



Overall Rating:4
Value Rating:5
Submitted by marcus a Audio Enthusiast

Date Reviewed: October 22, 2003

Bottom Line:   
awesome amp. crazy with power and hifi...

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Used product for:   More than 1 year

Duration Product Used:   Audio Enthusiast

Product model year:   1996

Price Paid:    $350.00

Purchased At:   private - in sweden




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