I like its very detailed tube-like sound. The sounds are warm, non-fatiguing, and very good low end. It has also a good power supply and difficult to overwork. Highly recommended! | Turf Installation

A bit heavy.

A slightly warmer sound than the Nelson Pass designed GFA-5xx series yet retains those amps' strong foundation and bass control. Tree Trimming & Pruning

No Complains at all

I bought this amp for $950 from an audiophile friend of mine who owns equipment easily over $100k. HR refuses to quote what's he's actually invested because it upsets his wife. He spends hours teaching me about this amp, about Nelson Pass, and alot of other stuff. I'm glad I bought it. He stressed that I start my audiophile journey by introspectively looking at the type of music I like, examining the frequencies, and then speakers that would cover those, then an amp that would drive those. For me, this amp has power, clarity and holds its own against amps that cost way way more money! In some cases, it sounds BETTER than amps costing way more. Really, the drawback and only negative I experienced was the heat! This baby gets hot hot hot! Don't stack anything on it! And font put it into a rack or other enclosure without a few on it. In fact, I'd say that a fan is needed for best long term performance.

Heat. Power consumption. Not efficient, but it packs a punch. Seems to sound better as you turn it up louder. Thus is NOT for small confined listening spaces/stages.

Smooth and sweet tube-like sound except with more authority in the lower registers. Sounds wonderful with the Magneplanar 20.7 but also sings with the 800 D3. A slightly warmer sound than the Nelson Pass designed GFA-5xx series yet retains those amps' strong foundation and bass control. Being voltage-driven devices (like valves), MOSFETS tend to be more tube-sounding and the 5500 exemplifies this. Bias (like other Adcom amplifiers) is toward class A, so it runs warm but not overly so. They won't heat the room like my old Krell monoblocks. But it's also smoother sounding and less transistor sounding than my Krells. I'd say the sound is smoother yet less veiled, more like a Threshold (which I ran it compared it to in my system). Highly recommended.

Runs warm, nothing else.

Clean detailed tube like sound (and have VTL MB 450s to compare to) can’t fault this amp at all its a classic Nelson Pass design!

Gets nice and warm otherwise perfect SS Amp

Warm , non fatiguing , very good low end . Very good power supply , difficult to overwork .

Sound stage and upper registry could be more detailed , but never harsh .

The GFA - 5500 is a 200 watt per channel version of the larger 5802 power amplifier. Both are based on a Nelson Pass 3 stage amplifier design that leverage MosFet (HexFet) outputs. These amplifiers are excellent. I had the prior versions (GFA555 series 2 and the 565 mono blocks, both bipolar). The MosFet amps render a smoother sound with more detail and a better soundstage with less listening fatigue than the bipolar based prior models. The MosFet series amplifiers have excellent low level detail as well as a smooth wide frequency response that is not fatiguing. These amps run class AB1 and run class A for the first watts out of the amp. The result is excellent sound reproduction.

These amps produce a lot of heat because of their bias running partially class A.

GFA-5500 is a very analog, smooth sounding amp with great dynamics. It might not be super resolving or studio grade accurate, but it just sounds pleasing especially in the bass area. After a couple of years of using it I am completely in love and I realized, it's the kind of sound I have always been looking for. It turned out to be a very good match with my Dynaudio Contour speakers too. For the money it's an absolute steal. And even for 4x the price it's still a very competitive amplifier, based on my personal experience. As to the maintenance, I only had to replace a few small capacitors, the big ones were like new, even after 20 years of use.

Runs hot, weights a ton, the military grade power switch, no power saving mode, no remote control

I paid $1000 for this amplifier a number of years ago. It's worth every penny of that $1000 today. I've owned countless amplifiers over the years and this one sounds as good as any of the best. The specs are first rate and the sound is accurate and powerful. Pair this amplifier with nice speakers and an ADCOM preamp I run the legendary ADCOM GFP-555II and the sound is unreal. I have had friends over to listen that cannot believe the sound this pair creates. You tell folks the price these go for on the used market and they are floored! ADCOM gear is truly and Audiophiles best friend.

I bought this amp new back in 1995 I guess, I realy cant remember exactly.
It have been hooked to a pair of Mirage speakers who is tough to make them "sing"
I tried out a number of amps but all of them were to weak not being able to make the umphf I was looking for. When I tried the Adcom amp I knew I was home, this was it, never ran out of power, to my neighburgs complaint, bas steady as a rock.
If any, there could be a touch of more resolution i in the highend, well well.
My preamp, a Edisone one, tube RIAA and a passive line preamp I used for quite a while.
When playing LP´s it sounded exellent! When playing CD´s it needed something else.
When I stoped buying LP´s I bought a Rotel preamp & a Rotel CD.

I still have it & I wont sell it