Adcom?

That's something I'm sensitive to, grainy or harsh highs.  I got rid of an Emotiva amp that got harsh at higher volumes and it drove me nuts because back then I was under the impression that all amps sounded the same.  I also had an Onkyo receiver that impressed me until I realized it sounded different than my main system.  Grain, I'd never heard it before and suddenly I realized that these audiophiles speaking of grain and such were on to something.

That's how I got turned onto Parasound.  Not harsh, just smooth full sound.   These days, for a preamp I've got the Parasound Halo P5 for the Adcom amp.  Not harsh in this set up.  But I've also noticed that the amp responds to different cables.  If I put in silver wire IC's and silver plated copper speaker cables, at least with my speakers it can get bright with some recordings.  With Morrow MA 3 and 5, and copper based speaker cables, there is no brightness.

I don't believe my old Parasound amp was as responsive to different cables, it's another way to fine tune the system.  I've heard tube components do have a different sound, but tubes are higher maintenance and such, not my cup of tea.

Any word from Adcom on who’s designing the new models ?

The new models are almost entirely based on the classic models from their heyday, except with upgraded wiring and circuitry to meet current safety standards, etc.  Also upgraded circuit boards.  Still, the new models have improved specs in some areas, so it's obvious that some engineers are tweaking them, but Adcom only ever refers to their team of engineers.  No names are mentioned.

Earlier I may have given the impression that tubes are less than ideal in my opinion, but it's obvious that many love the sound and options of tube rolling.  I'm sure the tube sound would compliment Adcom amps, if one rolls that way!

I've got 30 hours on the 555SE at this point, and I've been changing cables and speakers as I go so it's hard to notice if the amp is improving.  But I'll tell you this, Ascend Sierra 2 speakers do not like Wireworld Oasis 7 speaker cables.  Strangest thing I've ever seen in my system.  A muted somewhat non-dynamic sound is the result, but swap in the Tress cables and everything missing is back.  The Totem Rainmakers are fine with either cable but do sound better with the Tress as well.

All in all though, the amp sound quality is quite good.  Open, fine imaging, air around the instruments without grain.  It's obvious why this design put Adcom on the map back in the day.  I don't crank it up in my smaller room, though, peaks of around 82-84 db are enough for me.  There's an old review by Stereophile floating around regarding the original 555 in which much praise is offered, and favorable comparisons with the high end gear of the day.  I'd say it's worth reading.

In this hobby I've made some missteps, and it's my hope to leave my impressions and results here to help others like myself who are looking for good options.  IMHO, these Adcom amps are a worthy contender unless you're looking to achieve that last 3-4% of magic in your system.  In that case, a reputable dealer with experienced staff may be your best bet, along with a much higher budget.

I’ve owned the Adcom 555 since it was first made,bought it used. After reading a favorable review of a Musical Concepts Modified 555 in Absolute Sound I sent it too them and I had it modified. Very impressed with the results,gone was the grain in the treble and the bass had more slam and tighter. They made it dual mono too. I still have it in storage and I hard wired a Card as power chord into it.
I just got my Adcom 750 pre amp,a Nelson Pass design,back from Musical Concepts last month after having it modified to the Elite level and it sounds Uber. Sounds tube like with detail and warmth,very holographic with separation of instruments. I had owned the 750 since buying it from the first run with the Blue circuit board and Stereophile rated the 750 Class A.
Adcom was my first foray into affordable high end and holds a warm place in my heart.

My 1st post here. I've owned an Adcom GTP-400, & GFA 545 II since new around 1990. Thinking about upgrading the preamp & I'd like to stick with Adcom. Used GFP 555's seem to be around $350'ish, & 565's are $500 - $600. Adcom's site has their new GFP 815 for $399, but aside from a couple of threads on here I can't seem to find any reviews on it. Does anyone know much about this preamp?

https://www.amazon.com/Adcom-GFP-815-Stereo-Preamplifier/dp/B005Q36WXU/ref=sr_1_2?ie=UTF8&qid=15...

The reviews seemed to be mixed.  I was told by Adcom that another preamp model is coming out this spring.

I drive a pair of UK made EPOS ES22’s with a ADCOM GFA 555, what really makes it sound special though is the Modwright SWL 9.0 SE pre amp. The GFP565 pre amp is good, but the tubed Modwright makes it really show me how good the GFA555 can sound. 

The GTP400 (tuner/pre amp) is one of the worst sounding pre amps Adcom made (tough to pack eveything in one box and still make it sound good,... GFP565 blows away the GTP400 in terms of SQ it has a great phono section too)


Matt M

I thought I'd update my experience with the new GFA 555SE.  Once again, my system is a Parasound Halo P5, 555SE, Schiit Bifrost Multibit, Nad cd player(C565BEE) and Totem Acoustic Rainmakers which are bookshelf speakers that can get harsh with some material.

Cables are Morrow Audio MA3 and 5 both with Eichmann silver bullets for the RCA plugs.  Tress speaker cable which is Totem's similar version of Chord Odyssey.  It's a better quality copper with silver plating.

Anyway, at the 40 hour + mark, the amp has really burned in nicely.  The imaging from the Rainmakers are jaw dropping at times and vocals have that extra sense of realism.  Bass below 80 Hz is routed to the Kef Q400 sub, and in my smaller room, it's plenty.  But the amp barely gets warm now when at first it would warm up a little.  I can't say enough about the black background to the soundstage, and dynamics and PRAT.

It's worth a listen for sure.

I happen to have a pristine GFP-555 that I am willing to sell. Contact me if you are interested.

I believe Kalali is right on the money , i have a Adcom gfa 555 mk 2 and paired it with a ss  audio research ls3  and later a rogue audio perseus magnum preamp (tubed)  retubed w/ nos holland amperex bugel boy 12au7 , and boy did that ever liquidate the music thru the adcom, also connected my  B&K 442 amp to both preamps, again the tubed preamp creamed the ss preamp in midrange up thru highs. Poor mans james bond stereo ! By the way i long ago owned a gfp 750 mosfet adcom preamp paired with 4 nad 214 amps in strap mono thru a pair of paul barton psb stratus gold spkrs, that was my first dive into uh hum high end audio, for a very poor man at the time. Had a micromega stage 5 cd player and a rotel rcd 950 , the micromega was better, but the rotel fooled me for the 1st and even 2nd listen , but the micromega just had better midrange , rotel more boom and sizzle which sounds enticing at first.