Adcom GFP 555 II Preamp and GFA 545 II Power Amp Reviewed

Published On: February 14, 1992
Last Updated on: October 31, 2020
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Adcom GFP 555 II Preamp and GFA 545 II Power Amp Reviewed

One of the all-time audiophile classics. The Adcom GFA-545 (GFA stood for GREAT F****G Amp) designed by the legendary Nelson Pass (First Watt and Pass Labs) this was the best bargain audio in the world at the time. Read the classic review.

Adcom GFP 555 II Preamp and GFA 545 II Power Amp Reviewed

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Marvelling at the lack of speed which afflicts this industry, I'm pleased to note that -- at last -- Adcom has made it to the UK. No, I'm not wearing my Stars'n'Stripes necktie, but I do admit to above-average curiosity. After all, this brand is a market leader in the States, kicking serious tush in the sector best described as 'entry level high end'. Knowing about it mainly from the a heavy ad campaign and a run of rave reviews, I find that Adcom ought to have special appeal for the British audiophile: it's imported yet not expensive.

Sadly, though, for Adcom, it suffers not so much from the inevitable if slight price hikes as it wings its way across the Atlantic but from something unique to all imports into the UK. Even with sympathetic pricing, the Adcom -- while not entirely losing its bargain appeal -- has to compete with the toughest of our home-grown defenders in an area where the British excel: mid-priced separates from the likes of Exposure, Mission, Musical Fidelity, Audiolab, Arcam and every other audiophilic manufacturer which aims its wares at the hobbyist. And the British have had this market almost completely to themselves because the only other sources for cost-effective separates (Japan and the USA) have failed on either of two counts: lousy pricing or lousy sound. Aside from the presence of Hafler and PS Audio, the Yanks are barely represented in the UK at the sub-£1000 pre/power combination price point.

Additional Resources
Read a review of the Arcam FJM A18 Integrated Amp
• Read a review of the Anthem 225 Integrated Amp
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• Read many more audiophile preamp reviews from this resource page.


Adcom's GFP 555 II pre-amp and GFA 545 II power amp cost £499 each, for a combined price just £2 below the four-figure mark. And that tariff will pay for all manner of worthwhile British-made alternatives. But, immediately, you notice something about the Adcom combo which cannot be matched by British brands: it looks like high-end hardware. Most of the British, for whatever reason, continue to make gear which looks like -- let's just say that it's iconoclastic, which is noble if somewhat stupid. It limits the appeal mainly to British consumers who stubbornly encourage non-standard panel widths, unique colours and everything else which makes hi-fi mix'n'match an aesthetic nightmare. Adcom gives entry level buyers the look of pukka top-end gear, however boring the idea of a jet-black, 430mm fascia may seem.

The GFP 555 II pre-amp commits its first sin by including such anti-purist facilties as tone controls, a headphone socket, subsonic filter and tone contour, but it hastily makes amends by providing both a tone defeat and a second set of main outputs which bypass the tone and filter controls as well as the protection of the coupling capacitors. The sonic gains are obvious, so I did all of my listening with the amp connected to the bypass sockets. The pre-amplifier sounds dark, soft and thin when you feed a signal through all of the non-essential circutry.

The front panel is, indeed, loaded. At the extreme left is an on/off rocker and a power-on LED, the headphone socket (the 'phones run off a separate internal amplifier), balance, bass and treble rotary controls, tone defeat, contour (loudness), low filter, mono and external processor buttons, two rotary source selectors for play and record and volume control. At the back, the Adcom features gold sockets for phono (47k ohm/100pf), three line sources, two tape decks in both directions, the external processor and normal and bypassed outputs. Also on the back are an earthing post and a mains fuse.

The GFP 555 II uses a low-impedance power supply with enlarged traces on the double-layer PCB for minimal loss and improved stability. The power transformer is mu-metal shielded, so the sound is hum- and buzz-free. All capacitors are metallized electrolytics while the resistors are 1% Roederstein metal film types; so much for low prices precluding the use of designer components. The signal path amplifier uses premium grade ICs chosen for low noise, low distortion and low DC offset. All stages operate in Class-A and the entire signal path is direct-coupled when the pre-amp is operated in the bypass mode. The phono amp has been optimized for m-m and high-output m-cs; I tested it using Deccas, high-output Audio-Technicas and a Koetsu and found it adequate if not thrilling. This pre-amp is definitely a product of the line-level-sources era.

Operationally, the Adcom made me think 'Japanese', and that's meant as a compliment. No drama, everything worked as it should -- I'd forgotten what it was like to just flick a switch without shielding my eyes from debris or my ears from bangs and pops. Am I getting older or something?

Ditto for the power amplifier. After a few recent disasters, scale models of the bombing of Dresden, I've approached amplifier switch-on with dread. The Adcom? Not so much as a 'click', other than the mechanical sound of the rocker switch engaging. Again, this is hi-fi-as-appliance: A black box, ennui relief in the form of a grooved section on the upper half of the fascia, an on/off switch and LED indicator, a brace of multi-way binding posts and gold-plated inputs. Oh, and a mains fuse. The only other distinguishing characteristics are three warning lights, two for 'instantaneous distortion alert' to warn you of excessive THD, IM, slew-induced distortion or clipping, and a light to indicate the awakening of the thermal protection circuit. Even beating the crap out of this amp with some tough loads, I couldn't get the lights to flicker once. Which surprised me, because this amplifier -- though rated at 100W/channel into 8 ohms -- doesn't come across like a real piledriver. Even the literature mentions its suitability for non-headbanging conditions

Adcom's middle-of-the-range amp uses a Triple Darlington output stage, a large potted toroidal transformer and large, high-grade power supply filter capacitors to provide stability with awkward loads. While it didn't exactly make the Sonus Faber Extremas sing, neither did it pop its corks. There are no electrolytic caps in the low-frequency signal path or feedback loop path, with the only caps used in the circuit being precision non-polarized types. A servo circuit minimizes DC-offset at the outputs. Large heat sinks and adequate ventilation kept this cool at all times, even when the unit was attached to Apogee Stages. The output section contains 12 discrete transistors, and I'm assuming Class AB operation.

Time and again you're reminded that this is a middle-weight, mid-priced, mid-everything set-up. Despite lip service to the audiophile sector, the Adcom devices are too user-friendly, too tweak-free to frighten off non-hobbyists. If you look at the globe with the Japanese at one extreme and the British at the other, this American offering rests firmly in the middle. And not just in terms of ergonomics or perceived value but sonically as well.


If the characteristic British sound is one of coherence, top-to-bottom consistency and detail, with the Japanese sound being punchy but thin, bright and 'hi-fi', then this pairing provides a perfect compromise. More than competent but almost dismissive of subtlety, the Adcom sounds like a half-scale behemoth. While lacking the slam and sheer drive of the big Yank offerings, it does have more (subjective) kick than most British offerings, whatever palaver they may make about their Herculean power supplies. The Adcom is never ruffled. It merely knows its limitations. It will not ape 300W' worth of Krell or Levinson. Neither does it sound like a NAD3020 wishing it only had to drive headphones.

But there is, despite its feature-laden facade, a real sense of 'audiophile'. In other words, it makes all the right noises, with competence in certain areas -- of which the mass-market audience is ignorant but the hobbyist sector deems essential.

Using CD as a source and playing the Adcom through Linaeum LFXes or Rogers LS3/5As at 'sane' levels, it emerged that this amplifier enjoys great synergy with speakers which don't tax its lower registers and which possess stunning imaging capabilities. At no point do these speakers demand too much of the Adcom; allowed to all but 'idle', the GFA 555 II is a relaxed, relaxing performer which can handle quite large dynamic swings. It's quick without being breathtaking, and it's detailed without sounding over-etched. Juggling these qualities, you find that it's too 'musical' to be mistaken for any Oriental wares other than certain Marantz, Pioneer and Rotel units subject to known reviewer adulation. Conversely, it's too lively to be mistaken for a po-faced Britbrick concerned more with politeness than partying.

But it does have a 'personality'. The smooth, controlled sound stops just short of dullness, as if the designer consciously avoided exciting any tizz which could be mistaken for dialled-in hi-fi SFX. In this respect it does show a touch of Britishness. But the sound is, at times, too light, if not exactly washed out and thin. The lower registers have slam, power and control, but -- as shown by the Apogee Stages and the WATT/Puppy combination -- the real action is in the mid-to-upper bass, with the bottom octaves sounding drier and less visceral.

Which makes the Adcom a perfect match for smaller rather than larger speakers, but this is a byproduct of the sonic nature rather than the power delivery. Even so, this shouldn't present too much of a problem for British Adcom dealers because, conceptually, the products are far removed from the hair-shirt, circa '79 mentality of most of the British competitors. The Adcom products will appeal mainly to Krell/Levinson wannabees. They provide high-end karma at sensible prices, performance which must be taken seriously, benevolent ergonomics and perceived value which continues to elude the head-in-the-sand British makes. Then again, the looks alone will ensure that the Adcom never has to face off against its British rivals. I can only think of one range which would give the Adcom a hard time and that's Acurus. Which, fortunately for Adcom, isn't available inthe UK.

Does the Adcom package represent good value in the UK? Yes, but only if you can't bear the thought of giving shelf-space to ugly, unreliable, gutless, masochistic products aimed at xenophobes. Which means that you're part of the 99.999999999% of the world's population.

Additional Resources
Read a review of the Arcam FJM A18 Integrated Amp
• Read a review of the Anthem 225 Integrated Amp
• Read hundreds more amp reviews from
• Read many more audiophile preamp reviews from this resource page.

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