I have owned this amp for 6 years and have always been impressed. I recently tried the Cinema Grand and returned it 7 days later. Iam using the 555 with Definitive BP30's and it pushes them very easily...so easily I can unlpug the amp and it will continue to crank out the music for an additional 20-30 seconds due to its huge storage capacitors. For the money it can't be beat!

I havd both the 555 and the 555II, love them both. I use the 555II for the base and the 555 for the high's biamped on my Snell CIV's. Great bang for the buck.

A recent purchase from a friend, the three GFA555mkII's have been an OUTSTANDING addition to my HT system. The more recent addition of Def Tech BP3000's/BP2000's/ and the CLR3000 are driven cleanly - and in my opinion - sound incredibly on both music and movies. It's hard to tell if the bass output others mention is there in my system - all speakers have a built in powered sub.
I would definitely by them again, and I'm even considering two more - to have five bridged mono amps for HT.

power, bass, bullet-proof

a little harsh on the highs

One powerful hunk of metal. clean the whole way to the top. used it with b&ws and sounded good, if a bit muddy due to the speakers. use now with thiels and it makes the speakers sing! have used with friend's magnepan's and it also makes them sing. good base, nice punch. The drawback? a bit eddy or harsh on the highs. not too bad at low volume, but can get worse as the volume goes up. by no means is it terrible, but it is noticeable if you have a decent system. i can tell the difference betwene the 555II and the regular 535 (a very nice little amp). Don't get me wrong, the 555II beats anything in its class like yamaha or nakamichi or etc., but I have to point it out for the record. thus 5 on value and 4 on overall, taking into account trend to bump things up here.

Similar Products Used:

adcom 535, nad, yamaha, nakamichi

I bought this amp for $550 8 years ago and it's never let me down. I run it thru 4 Infinty SM152's. I also use an AudioControl Phase Coupled Activator that has a 30hz chip in it. Needless to say, this setup will crack house foundations if allowed! If you want a LOT of bang for little $$, than this is your amp!

I have an old Adcom GFA 555 Mk. II that I use now and then. I recently have been trying different speakers including some which need tons of power, such as the planar magentic Magnepans and electrostatic Martin Logan Sequel II's. These speakers NEED power, so I discarded my expensive tube amp and hooked up the Adcom. With these speakers power delivery is key so that is what this review
is focused on. We have all played our stereos loud before, but have you tried playing inefficient current-hungry speakers to full output?
First, the Magnepans (MMG's). The 555 II took on these 4 ohm speakers with no problems. It caused the ribbons to vibrate virtually off of the frame! They say these speakers have no bass. Not true, it you have power you can launch some great bass off of these. Highs were sparkling and there was no problem with distortion of any kind, until the ribbon drivers made scraping noises when stretching
to their limits. The amp got warm, but not too hot to touch the heat sinks. It sounded great.
Now, the Martin Logan Sequel II's. While the Magnepans are full range quasi planar magnetic, the ML's are
very different they are part planar electrostatic and part dynamic. The Magnepan panels are observed to vibrate when driven, but the ML's "shimmer" when played very loud as they function at higher frequencies and a normal woofer takes over the bass. I found that these were much more difficult to drive. The Adcom playes these highly inefficient speakers to ear-ringing levels where the panels were shimmering every time Neil Pert hit a rimshot. Lights were dimming in my house for every bass drum beat, and
the heatsinks got too hot to touch. Acoustic guitars jumped out of the speakers into your face. The bass remained tight and well-defined. These speakers suck up the power like you can't imagine. I was wondering how my CD player kept going as the amp was taking all the power in my house! The thermal protection never kicked in and the distortion lights did not illuminate, but you could feel the heat rising out of the amp and it was very hot. You are not supposed to bridge this amp unless you have an adcom-fan installed.
Right. I bridged it into one Sequel II, driving over 500 watts into the speaker. The transparent
panel seemed to take on a life of its own as it danced around, I even got some good "impact" out of rock music, somehting that supposed to happen with horn speakers not electrostatic speakers. The Martin Logan did not make the scraping noises that the Magnepan emitted when near its limits, but the amp's heatsinks were so hot you could burn yourself if you touched them, like an electric stove burner. It didn't seem to mind. I played it like this for
about 45 minutes thinking the thermal protection would kick in and it did not. The highs were detailed and
the bass was very deep and clean. I did not hear any distortion.

This amp is rugged, clean and well-designed. With proper ventilation (I had it on the top of the rack so its heatsinks were working at top efficiency) it can push out the power like almost nothing else, certainly nothing else in its price range, which is very low (like 500+) on the used market. It sounded great too. Admittedly, it was not as detailed as my tube amp, but it still impresses me even though it is over 5 years old, maybe 10? This is why I have not sold it. If you have ineffecient speakers like the Martin Logans you are well-advised to get two 555 II's and use them bridged or in a biamped configuration as many have done on this site. Even at normal sound levels the 555 II played for about 8 seconds after being turned off. This amp is already a classic and I can see why.

Clearity,Power,Durability and Price

Reveals weakness in other components or speakers

Very nicely made amplifier. Very clean sound with alot of punch on the lower end. At this price point dont believe there is anything out there that even comes close. Sure there are nicer amps out there but at 3 times the cost. If you are looking for a well built amp that will last many years and has alot of clean power look no further.

Similar Products Used:

none at this price point