This thing is a rockstar! It's got the same board as the GFP 565 reference unit. It's got an ALPS volume pot. It's got THE BLUE BOARD! Gold plated connectors. Discreet circuits. Quality Japanese capacitors and resistors. If you were to produce this unit in 2014 it would cost you $1500. It's a bargain at $400 on the used market. The headphone amplifier is wonderful and the phono section is among the best I've ever heard. I cannot recommend enough. This may be the best hidden gem in audiophile preamps. Don't believe me? Try for your self. Be sure to open the case and take a peek inside for your self. The quality is striking.

My rating pertains to the 1986 gfp 555 unit re-capped so this may not be a fair review.Anyone reads my reviews they'll see I'm a firm believer in good capacitors.There was a time when I thought Adcom was lousy sounding equipment from what I've owned in the past.Not this 1986 preamp after I replaced every electrolytic capacitor with some bypassed with polypropylene caps which has elevated it to a whole other level in performance.

In stock form it was flat or dry sounding and had crappy Jamicon capacitors in stock form.Now,it has incredible sound which once again proves my theory: great circuit design with the sound being compromised with cheap capacitors.I guess the company has to cut cost somewhere and they did this with the capacitors.Many do this by the way not just Adcom !

Now,it has very clean bass that has a fast tight sound.Not bloaty at all.The midrange has a very relaxed sound.Treble is much cleaner which helps with 2 way speakers.

Frankly,this has turned out to be one of my favorite mid fi preamps I've owned yet and I've had Luxman, Yamaha, and Onkyo in the past.Also, re-capping it has extended the life of the unit.You become so accustom to the sound of your equipment to the point where you dont realize the sound has degraded once this equipment starts aging and caps have a limited lifespan moreso than other parts.

It truly delivers beautiful sound to my ears now and is so much more dynamic.This preamp has quite a simple circuit and no where near the amount of passive compnents vs. other units I've owned.Sometimes less can offer more if the circuit is designed well.

It has tone controls and a loudness they call "contour".The tone controls can be turned off for the purist that dont like "colored" sound.Has phono,cd,tuner,auxillary,and two tape inputs as well.The only thing missing is a tuner but i'm not a radio person so no love lost there.

If you have the means to obtain one of these and put decent quality capacitors in it I doubt you'll be disappointed.In fact,you'll be pleased and I cant put a dollar amount on how much one would have to spend on something new to equal the sound of this now 22 year old preamp.

For anyone interested in what parts I used.Nichicon vr series for the main power supply caps.I bumped up the size to 6800 uf and added Dayton poly caps for better filtering.The rest used in the signal path and other areas were Rubycon zl and Elna Silmic II and some of these Ii added Kimber caps.It made quite the difference !



Strengths:
great dynamics across the board in general.

Soundstage depth and width.

Ugly face.

I placed bids on eBay for a GFP-555II for several months finally winning this unit for my $100 limit. I wanted to try an Op-Amp based preamp to see how the sound compared to vintage solid state and tube preamps in my modest collection.

It sounded very good at first listen and the equal to a modified Marantz 7T SS unit but without the warmth of a Dynaco PAS-3X. After a few days, the depth of the soundfield increased with improved side-to-side image. After a couple of weeks, the GFP-555II became a keeper and my favorite preamp.

It works best with a tube amplifier and the favorite here is a vintage Conrad Johnson MV75A1, 6550-A based 75 w/ch driving Klipschorns. Wow!

Highly recommended for those who love the advantages and mix of solid state and tubed components.

Similar Products Used:

Marantz 7T
Dynaco PAS3X
NAD 1020
Dynaco PAT4

Reasonably cheap

Dull, Doesn't have that Hi Fi sound

Had this in my place with a matching Amp the GFA 555Mk II. I have to say that I've always been an Adcom fan due to their price to performance ratio. i've had many experiences with their amps particularly the 545 and the 555 which I always recommend w/o hesitation. This preamp? well....... It's Ok but couldn't really say it was at par with some of the other products i've tried from their company. I matched it with the gfa 555 and my Audio definition floorstanders and compared it later on with a budget tube preamp the Dynaco PAS3. The result was not good. It GFP55 was annoyingly Dull and Veiled. Yes it handled the extreme really well and not as annoyingly bright as most SS preamps but it just didn't have that life giving magic. Details were not as crisp and transients was like watching a boxing match where fighters had pillows on their fists. Maybe I just got a tired example. I couldn't find any redeeming quality. I would recommend other vintage SS products within the price range that could pull it's panties down. Such as: Used Sonographe, Any Superphon especially the revelation, NAD 3020 used as pre and the Metaxas Marquis

Similar Products Used:

All the preamps mentioned above including ARC-LS2, LS7, SP9Mk 2, Audible Illusions Modulus 2A, Le Tube, Paragon, CJ PV10A and the lazarus

Cheap

Sound

Ouch. The only preamplifier I’ve owned that sounded worse was a Carver C-2. This makes my speakers sound like tin cans on wax strings. The sound is too forward for my taste. Maybe it sounds good with heavy metal or rap?

Similar Products Used:

McIntosh C-36, Mcintosh MX-113, Carver C-2, Adcom GFP-555.

Simplicity, aluminum construction, gold plated outlets

None that I know of...

Outstanding unit. Being used with 2 GFA-555II''s. The sound and versatility is astonishing.

Similar Products Used:

2ea GFA-555II''s, HK7600II CD machine, Polk RT1000i, Monster Z-cables

Simplicity of selections. Ability to disable tone controls.

Overall a very clean sounding preamp. Easy selection of inputs and recording modes. Simplistic but highly functional. Few extraneous frills to complicate what should be pure sound from the source.

Convenience, build quality, price ($600)

Sounds less good than passive preamps

I want to add a few more positive notes :
- This preamp looks like an Adcom GFP-565 (Class B Stereophile), sounds 99% like it, has the same internal typology and shares 95% of its high-quality components
It seems that the GFP-555 (first version) was very different and inferior.
- I was disappointed because I compared to a Quad 44 (exceptionally good) and a direct link CD-Power amp. But compared to other active preamps between $400 and $800, the GFP-555-II is good sounding (better than most "made in Japan" preamps) and has a lot of nice features (phono input, 3 loops, 2 outputs, headphone output, tone control, etc.).

Similar Products Used:

Quad, NAD, Adcom

I'm using the 555II in conjunction with another vintage piece of audio gear, an NAD 2400 PE amp. I replaced my second system which consisted of a Creek 5250 integrated, Stereophile and Fi recommended. The Creek had great resolution and good clarity, but was ultimately lacking in soundstaging, bass and dynamics. I've been very happy with the Adcom, it allows much more bass extention and soundstage depth through my Paradigm 9SE speakers than the Creek could produce on its own, and the dynamics are incredible. It has a fine phono stage and the headphone out allows for a much richer and fuller sound through my Grado 125 headphones than the Creek ever produced.

For 200.00, I don't see that the Adcom can be bettered. It allows the power of the NAD amp to really come through, with clarity, richness and dynamics. It is a full featured preamp with Lab output to bypass the tone controls and comes with an excellent phono stage. Beware of modern integrateds that cannot match the sound of cheaper, older separates.

Four stars for a fine budget performer that might be a little veiled in comparison to the newer stuff, but a bargain to look for nonetheless.

I bought this preamp to match my Adcom GFA-555 amplifier. The preamp has been adequate. Not having the funds to experiment with a variety of higher priced preamps I have not noticed a degradation in signal.Based on price and perceived quality I would rate this 4 stars leaving room for the outside chance there may be something better in the price range.
I do believe Adcom is leaving it's niche market as an entry level audiophile product. Only time will tell if this is a wise move, competition is stiff at the higher price points.