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Which Adcom amp is best?

According to the story, the Absolute Sound asked Adcom for an amp to review. They could have chosen a 555, or a 545, but instead sent a 535, which received a great review. I have owned all of them, including a pair of 555s strapped for mono, and a pair of 535s for bi amping. I now run a 545 and love it
 
I currently have amps from their new line. The 555MS(125 wpc), the 565SE(250 wpc), the 6002(70 wpc) and I had the 555SE( 200 wpc). The best sounding of the lot is the 565SE. Great detail with control, air without harshness, its a terrific amp. The 555SE has a touch of warmth by comparison, though that might partly have been the Parasound Halo P5 too.
 
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I've got the 565SE mated with a pair of Infinity P362 from about 2010. It's a tower with 2 6" 1/2 drivers and a 3 inch midrange, all aluminum cones. Rated for 200 watts. 4 ohms and these things can take the power. Really clean and dynamic sounding with the Adcom, which btw has a tube preamp(Schiit Freya+). Those that speak highly of a tube/SS combo are really onto something, when I engage the tube circuit I'm finding real magic happens, and I've never experienced that before. I'm loving this set up!
 
A while back, I acquired a damaged 555II from Bartertown, then worked with an exceptionally kind and talented AK member to restore the magic smoke to its rightful place. Sounded great! I had no qualms about setting up my best friend with his first adult hifi system so I shipped this amp and its matching preamp off to Michigan to be set up in his studio. He loved the retro 80's styling and overall high quality of the pieces. We paired them with a set of Dynaco A25 speakers, stands and a Techics 1600 that my uncle graciously supplied from his collection. (Thank you Uncle Fred!)

No joke, it sounded jaw-droppingly amazing in his space. He heard details in his favorite tracks that he had never heard before! It was everything he could not have imagined audio could be until... *POP * *POP!* *poof!* The whole rig went silent. All drivers of the A25--dead. 555II? Smoked, no output. What the hell happened?! Did he cross the wires at the output? Was there an electrical surge? He's a conservative listener so the volume knob wasn't cranked.

Damn you 555II!! At some point I'll be able to ship this back to CA to determine what went down and if it's worth repairing. Likewise the A25's will have their drivers replaced and live again. Perhaps this type of system is too fragile for a beginner audiophile? If I am able to resurrect the 555II I will think long and hard about pairing it with uncommon speakers again.
 
Maybe it's just me, but I would be cautious about buying a 30-40 year old amp and using it as a main amp. Unless it's totally reconditioned with all caps replaced, and any known issues of the old Adcom amps dealt with.

I did buy a 20 yr old GFA 5400 a couple of years ago. The DC offset at the speaker terminals was high on one channel and I could not adjust it down enough. I found it for cheap, and it was an experiment to me to see what the old stuff might be like. It sounded fine but I didn't have the skill to rebuild or restore. That's why I went with the new stuff. It is built with current safety standards, and the fact that it's new means it's good for 30 years depending on power of/off cycles.
 
Yep, if you are not careful an Adcom amp will kill your speakers....I know this from personal experience...MartinLogan, Lowther, Triangle, all have been mercilessly executed by a 555II, a 535, and a 555SE, in that order...except for the 535 the faults were external (read as a loose nut moving the cables while system powered up!), but still these amps will pump out a lot of current in an "incident" and the drivers that aren't capacitor coupled are gonna take a hit.
 
Really, any amp with 200+ wpc and a huge power supply with big caps will do damage if you're moving cables around and something bad happens. And anyone, never disconnect or connect ANYHThING while your system is on. With the Adcom amps anyway, wait a good minute after power down as the caps discharge before disconnecting speakers, and longer if opening up the hood.
 
Unfortunately stereo gear doesn't last forever. That 5503 is about from 95-96 or so, which means it lasted 25 years. Either get it fixed or buy something else, you're still way ahead of buying a boutique brand 3 channel amp which would have costed $3000+ vs $1299 for the Adcom, or less if you got it used.
 
gongli said:
I listened to an Adcom amp - pre and power yesterday, and I am smitten with them now. I love their clean, clear sound, with black background. It reminded me of a diamond...

I listened to other great amps like McIntosh, Krell, and Audio Research, and I still prefer the affordable Adcom.

So, my question is which one should I hunt down?

GFA 555
GFA 555 II
GFA 5500

Thanks for your time...
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motorstereo said:
Correct:yes: And those same 2 people also prefer to have their barbecues outside:D
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I am the original owner of an Adcom 555 ll. It’s currently powering o pair of Magnepan’s MG12/QR speakers. I bought this amp new. Has not been serviced( yet) and is still going strong. I’ve checked the boards and caps for the dreaded leakage which results in frying your speakers but there is none. It will eventually need to be recapped. But it hasn’t given me any problems other than replacing the fuses when I accidentally shorted them. The fuses for the output rails are on the back and are easily replaced. The newer amps have those fuses inside. If you find a good amp have it checked out first. If you want speaker protection there was I guy who made speaker relay protection circuits for these amps. You might want to search for it.
 
Gaerisch said:
I am the original owner of an Adcom 555 ll. It’s currently powering o pair of Magnepan’s MG12/QR speakers. I bought this amp new. Has not been serviced( yet) and is still going strong. I’ve checked the boards and caps for the dreaded leakage which results in frying your speakers but there is none. It will eventually need to be recapped. But it hasn’t given me any problems other than replacing the fuses when I accidentally shorted them. The fuses for the output rails are on the back and are easily replaced. The newer amps have those fuses inside. If you find a good amp have it checked out first. If you want speaker protection there was I guy who made speaker relay protection circuits for these amps. You might want to search for it.
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I've got 3 although all were bought used and none were touched before I bought them.

I'm currently doing some mods/upgrades/recapping of one and will eventually go through all three. None of the caps in the unit I am working on showed any issues at least visually, I didn't test any of the caps.

There is an Adcom model that is notorious for leaking caps but that is the GFA-565.
 
2026 checking in...
I bought a pair of Thiel CS7 beasts in 2024 and the amps I had on hand wouldn't drive them to satisfying levels (125wpc Parasound & a 150wpc VSP Labs). I found a 5800 for sale locally and bought it. At 250wpc at huge current capability it does the trick.

I opened it up on the bench and found a dark resistor on the center pcb. I replaced it, along with the transistor, as a precaution. I also tightened up hardware, replaced one of the 2 pairs of output binding posts, and replaced a cracked fuse holder. The original fans were pretty noisy by now so I replaced them with low-noise brushless versions.
I adjusted the bias and offset per the manual. The amp puts out 315wpc, at the edge of clipping, into 8-ohm loads.

This heavy beast has been giving me good service since. I did have to repair a woofer ($750!) but that was caused by a faulty DAC that sent a DC pulse out that drove the voice coil out of its gap. The amp did a swell job amplifying the signal it was sent and it's debatable if ANY protection circuit could have acted fast enough to save the woofer. You overly-cautious types might want to add "no DC-coupled designs" to your list of topologies to avoid.

20251024_180015.jpg
 
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Bostown said:
Certainly mine haven't been damaged. I'm running a pair of 555's alternating their use from Bridged mono or as in the case today. using them in stereo to bi-amp a set of Henry Kloss' original 4 piece Ensemble speaker system. ( arguably the only way to really get them to perform at their peak).

There's certainly a lot of web chatter about the "Potential" for damage but I've yet to read any actual accounts where someone has experienced it with the 555 ( not the II). I've read the same web chatter warnings about the Phase Linear 700 B and Crown DC 300. Never had any issues with those amps either when I owned them. Maybe I'm just lucky.

I'm all for the recap idea, if nothing more than to keep things fresh under the hood. given the age of the 555 , it's well due.
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A note: Read the manual for the Crown DC-300 (It applies equally to Adcom owners). Crown recommended fusing the speakers as a form of speaker protection. Note, I am not dissing either make in good order. They do perform well. Fuse Thy Speakers. The unobtainium driver you save may be your own.
 
I have been enjoying the sweet sound of a GFA-5500 since purchasing new in 1995. Absolutely love this amp, excellent bass, clean mids and highs, no complaints whatsoever. But I am realistic and know that it is due for a recap as it is over 30 years old. It will probably be on the bench this Fall.
 
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