Adcom GFA-5802 -vs- Parasound HCA-3500 Amps?

More opinions please:
Has anyone out there owned both the Adcom GFA-5802 300 watts per channel power amp and the Parasound HCA-3500 350 watts per channel power amp?
If so, how do they compare sonically head-to-head?
What are the sonic advantages and disadvantages of each when compared to one another?
Thanks in advance.
Funny, I just had a salesman talk to me about the Adcom 5800 and 5802 yesterday as he was giving me info for a friend; both he and another saleman agreed that the 5800 was better than the 5802. Sorry I don't have info directly to your question but thought i'd share this experience.
I've heard both of these amps, and I'd give the edge to the Parasound 3500. The Adcom 5802 is still a good amp (and a great value at used prices), but it's a bit warmer and darker than I like in my system. Both have good dynamics, good soundstaging, and accurate timbral presentation of instruments, but I think the Parasound is more transparent and neutral than the Adcom 5802. When I auditioned these amps in my system about 2 years ago, and A-B'd the amps, I found the Parasound "disappeared" better than the Adcom.

Brian's comment about the two salesmen who preferred the Adcom 5800 over the 5802 is interesting -- the sales folks that I know have had the opposite reaction. I think that Adcom had repair problems with the 5800 (also true of the GFP-840, their first true pre/pro), and made some subsequent circuit and parts changes in the 5802.
To Sdcampbell (and others), I want to reiterate that I have never heard either, though I do trust the salesman that mentioned it to me, but I can't say anything for fact. They mentioned something like the 5802 is more power and weighs less, that alone puzzled them (or rather, spoke volumes). Anyway, sorry if I caused confussion. (He further stated that the 5800 can be nicely modified.)
This is a great comparision between products designed by two of the best audio engineers out there i.e. John Curl with the Parasound and Nelson Pass with the Adcom. As has been stated by both John and Nelson, they simply provided the design for these products. How closely each manufacturer followed those designs, how well they laid the circuitry out on the board, what grade of parts were used, etc... is all beyond the designer's control

Getting to the meat of the situation, in my opinion, the 5802 is sonically superior to the 5800 by a noticeable margin. Having said that, I don't really consider either amp to offer "good" sonics, regardless of what the reviews say. Personally, I find this very strange as i am typically a big fan of Nelson Pass' power amps and the basic design of this amp looks to offer great bang for the buck. Then again, see the above comments pertaining to how much actual "control" Nelson had over these products.

In my experience, both of these Adcom's tend to fall apart at a progressive rate. That is, presentation sounds less "unified" or "cohesive" as drive levels are raised. The treble and upper mid gets harder with more grain and midrange loses the little bit of liquidity and warmth that it might have at lower volumes. Bass is bloated and lacks definition at any given volume, but gets worse as spl's are increased.

The lack of bass control and definition really becomes apparent as one uses lower impedance / multiple woofer speakers. That's because such a design will pull at least twice as much current as a lighter, more manageable single woofer / higher impedance speaker would. Given that it takes surface area i.e. multiple large pistons to do bass with authority, and people buying this much power typically aren't using mini-monitor type speakers, the end result isn't quite what i was hoping for.

As a side note, i've cleaned and repaired a couple of these amps. Both models have forced fan cooling and tend to collect quite a bit of dust internally. The power switches on the 5800 tend to fail from what i've seen. While these aren't hard to replace and Adcom is great to deal with in terms of customer service / parts availability, it still shouldn't happen.

Based on past experiences with multiple different units, i think that Adcom did better with their much older Bipolar transistor designs than they do with Mosfet's. This isn't to say that all Bipolar's are better than Mosfet's, but in these specific designs and they way that they are implimented, that's my opinion.

Moving over to the Parasound, I haven't heard an HCA-3500 although i was interested in purchasing one several years ago. Having said that, i would hope that it sounded better than either of the Adcom's and "think" that it probably does. I do know that the 3500 is a TRUE dual mono design, utilizing dedicated power cords, transformers, power supply filtration, etc... for each given channel. This amp is basically an earlier "baby" version of the JC-1 monoblocks, using a similar design but built with "budget" parts ( compared to the JC's ) and crammed into one chassis. I do remember Bob Crump making a few simple yet highly beneficial modification suggestions about these amps over at AA, so if you have one or are thinking about buying one, you might want to do a search over there. Something about changing a couple of resistors, etc...

As a point of reference, John Curl, who designed the dual mono 3500, is the "Father" of all dual-mono designs. He was responsible for designing the first TRUE "dual-mono" stereo amps ever marketed to the public. Since we're on this subject, let me climb behind the podium for today's lesson : )

While "dual-mono" designs do have their benefits in terms of reduced cross-talk / improved channel separation, potential for improved imaging, greater current delivery, better control over the speakers, increased stability under heavy loads, etc... a lot of how much of a benefit ( if any ) that will be will have to deal with the total capacity of the power supplies involved. A single massive transformer with a huge array of filter caps shared between two channels could actually be superior to a dual mono design using scrawny transformers and minimal power supply reserve for each dedicated channel. Such is NOT the case with the 3500, but don't be fooled into thinking that "dual mono" or "individual power supplies for each channel" is necessarily "better" than a common supply. As i mentioned, all things being equal, "dual mono" or the equivalent for a multi-channel design, is "typically" desirable with all things being equal. Then again, how often are all things really equal??? : ) Sean
Ehoehn: Hmmmm... i must be confused / getting senile. I thought that the 5802 also had fans. I can specifically remember the 5800's having dual fans ( one per channel ). Either way, thanks for correcting me. Sean
I have had both amps in my system for a period of time.
The Adcom is a nice amp, but Parasound is definately a step up in sonic quality. Both amps are rated at similar power levels but the Adcom does not sound as powerful. On the used market now the 3500 is a no brainer unless you are considering stepping up for a pair of the JC-1's which sound really great!

I had the 5800 for some years andwhen it needed repaired, is where it started.Adcom wanted 450.00 flat rate and over 100 to ship it there and back.As we know you can get a used one on here for that.After telling Adcom that a used was same price there was no help.They did refer me to a repair center that kept it for a month and told me it could be fixed for half that .When i went to talk to repair center they havent even opened boxd..So after that I was done with Adcom. Now for the good news I got the 3500 last month and there isnt any contest the parasound runs circles around the adcom and the guy Tony at parasound is great, so beware if you get the adcom and it breaks. my friend has the 5802 and he isnt happy theres my 2 cents worth
I'm in favour of the Parasound as well. I have heard the 3500 beast & another 5-ch Parasound. Also heard the smaller HCA-1000. All this at a dealer's show-room.
For the price, I was very impressed w/ the sound. They seemed to be engineered correctly. Their power supply seems to be desirously over-built. Cost is kept down by manuf. in Taiwan.
I have heard some Adcom but I can't say that I remember the sound!

Your point about "dual mono" is well taken. Look at another excellent Parasound design, the 2200ii. It uses independent torrodial transformers, one for each channel. After the transformers, the power supplies are completely separate.

The only thing both channels share is a common chassis and a power cord.
I am not addressing your question, but why not an Aragon 8008BB? I had the same issue a few years ago. I read somewhere that the total capacitance for the HCA-3500 as advertised by Parasound is not made up of only the main big soda can caps. Maybe I am wrong but worth it to double check.

Parasound service is five star though.
bringing back a old thread :)

I have a adcom gfa-5500 & parasound hca-1500's

parasounds sound a lot better across the board with MUCH better low end, powering old infinity kappa 8.1 speakers. My adcom (which I love in my car) now is sitting in my garage for music/
Parasound amps are not the most durable ones - they tend to break down quite a bit.

I would look at either Acurus or higher Aragon as mentioned above.
Liquid-smooth..."Parasound amps tend to break down quite a bit" completely false..having owned two Parasound amps
and three Parsound Preamps during the past 23 year's I found their gear to be the most reliable and stable high end budget components on the market. Parasound has a long standing reputation for ruggedness and reliability. Their amps are very DURABLE and have a unmatched reputation for
consistent quality over the years.
Plus 1 on the reliability of Parasound. I sold and installed Parasound into hundreds of jobs and it was extremely rare to have any kind of problems.
Reviving. The hca 3500 had 120 amperes peak per channel. Anyone know this value on the 5800? Using a 5800 on my 3.6 which drop to 2.4 ohms