Eighteen International Rectifier Hexfets (per channel) can't be wrong.

Simply the finest amplifier I've ever heard. And that includes Macs, Brystons and a Krell or three.

They are not neutral, nor especially analytical. But they are is brutal in the bottom octave. Google the White Paper. The amps they can deliver (even into a single ohm for short periods) is nothing short of miraculous. Like my favorite Receiver (the SX-1980) the Mac's I put them up against current limit for self-protection. The Sunfire's Stereo Sig's self protection is it'll throw your 20 amp breaker. (And I wouldn't run one on a circuit with less than that, or you're not hearing it's full potential.) I would seek Bill Flannery out if your amp has seen hard usage. It's an investment in another twenty-five years of flawless service. IF it's low hours/driven on Sundays, then I'd say it'll last you the rest of your life as is. If you don't know its history, then here are a couple of things I've found that make a difference: 1. TIGHTEN THE TRANSFORMER SCREWS ON THE BOTTOM. If you're hearing a hum/buzz it's very likely not a fault issue, the transformer's probably vibrated loose. 2. Clean all the fuses and holders. 3. Tighten up the connections at the (detachable) AC cord/inlet interface. That can be tricky, and if you're not comfortable with doing without damaging the prongs of the AC cord inlet, don't mess with it. I tightened mine up by (gently) twisting them so they would have a tighter contact with the contacts inside the AC cord. I wanted it to be a little "grippier" than it was from the factory. I do the same thing with all connectors. Tighter's better, short of overdoing it so it pulls the interface out of the component. Enjoy! I have two (400x5 and 600x2) and they're the last amps I'll own.

UPDATED REVIEW ; HAVE PURCASED SECOND UNIT FOR OFFICE. REPLACED KRELL KAV PREAMP WITH CONRAD JOHNSON PV 12 AND PV 10 FOR MY OFFICE

NO ON OFF SWITCH

UPDATED REVIEW. ADDED CONRAD JOHNSON TUBE PREAMPS PURCHASED FROM DR. JACK AT THE SOUND FACTOR ENCINO. UN BELIEVABLE CHANGED FROM KRELL KAV PREAMP. MY SYSTEM HAS ARRIVED..
WILL PURCHASED THIRD FOR THE BEDROOM SYSTEM.
UNBELIEVABLE...UNBELIEVABLE...UNBELIEVABLE....
FROM HARD ROCK TO MOVIE SOUND TRACTS MY SYSTEM KICKS ASS.

Absolutely flawless to my ears. It's effortlessness is unsettling to those who aren't accustomed to hearing "non-electronic sounding electronics. It literally disappears.

None that I can discern other than no friggin' Power switch.

Unbelievably great imaging, wonderful layering of soundstage depth and width and (most impressively) Height!
My Apogee Duettas have never sounded so dynamic! I have also heard this amp drive a set of Monoliths and I found it to be a very symbiotic match, controlling the beasts in their owner's estimation better than the Crown Macro Reference he was using at the time.

Similar Products Used:

Mac MC1000,Adcom 5802,

The Classe CA300 is a quite massive piece, built to last with understated elegance. It plays with great ease and refinement into my Paragon Regents, and I have also heard it with Ariel 10's, and Thiel 7's, where it was wonderfully rich and musical. Great bass controll naturally, and very delicate, deep and wide soundstage. Double bass just seems to exist right there in the room with you, this amp has created a more convincing illusion of reality in my home than anything I have tried or owned. It is, to my ears, a great amplifier, free of any tube/SS arguments, it just makes the music, and puts it out there , calls no attention to itself, and what more could you ask? I have been going from amp to amp for years. I feel that for the first time, this one I will live with without constantly wondering, what am I missing, could this be better etc. It is just a fine product.

Power

Opaque sound, slow, disappointing bass

I compared the Sunfire Signature with the Musical Fidelity A3cr, and it was no contest. The MF is much faster, detailed, lively, and smooth. I cannot agree more with a reviewer that said the Sunfire made the speakers sound as if they were within carton boxes. In fact, I said the same thing earlier today, before reading that review. When I switched to the Sunfire, my girlfriend, who was in the other room, immediately shouted "What happened?" She composes classical music and has a terrific ear (much better than mine). She was even more adamant against the Sunfire than I was. I also agree with those who said it does not provide a high end experience. It lacks detail and delicacy.

There was only one area where the Sunfire beat the A3cr: bass. Even so, I did not find the bass of the Sunfire fully convincing. But I admit this could be due to the deficiencies of my speakers in this area. The A3cr is rated at 120W/channel into 8 ohms and can be "bridged" as it has outputs on the back that you can connect to the other channel's input. Since the A3cr costs $1600, maybe one could get better bass by buying a pair and using one to drive each channel, and still be at a reasonable cost level. I don't know if that would provide enough bass, but I know I would not buy the Sunfire.

I have not tried biwiring. I tried both the current and voltage outputs in the Sunfire. I also tried the normal and lab inputs. Could not hear much difference between all those. Most of the listening was done with current/normal.

The A3cr's are loaners. My VTL 300s are out for retubing. I will post a review comparing those when the VTL's are back.

Equipment:
Cheap Sony DVD player (as transport)
Perpetual Technologies PA-3 DAC (my PA-1 went bust and is being fixed)
Wireworld and Straightwire interconnects
Tara Labs speaker cables
Martin Logan Aerius i speakers

Similar Products Used:

Musical Fidelity A3cr

Everything. No sonic weaknesses that I can discern. NE PLUS ULTRA. There is an engineered Gundry dip of less than a db around or just above 1k, But I can't hear it and if Bob had just kept his yap shut I'm sure just about nobody would've noticed it.

No #$%@&& Power Switch! Also, I miss the Lightstar watt meters but I guess the concept of actually running out of headroom on this amp is pretty much a joke. Your speakers will cry out loud for mercy if pushed too hard by this amp. And you better believe it won't be from Square waves.

Please note: that this review is of the "Signature" amplifier. (borrowed for a short time prior to online used purchase,Thanks Jack!)
Basically, this is to offset that ridiculous "ping" posted right before me (though elementary statistics will tell you
that it doesn't really work, which is why it happens in the first place).
The only amps that MIGHT control a persnickety speaker load better than this amp does in stereo are the Mac and Krell mono blocks. If you buy two of these and bridge 'em(I assume they'll bridge, but WHY?) my guess (I admit I haven't bought a second yet, as the folks in neighboring towns don't appreciate their lights browning out to the distant sound of the Telarc 1812)is the Sunfire product will kill those as well. Check out the TAS reviews of both units. For once right on target. Even though to my ears they make too big a deal of Bob's engineered "Gundry dip", probably just to discourage him from talking so much. (They really seem to hate that, though they should stop, because,it's precisely what they do for a living) If they could design a Class A (quality, not class of operations)amplifier(turning their reaction to the Carver challenge back on them)then WHY DON"T THEY? The last amp I plan to buy. One for the ages.
Or to summarize to "Whomever": Sunfire make good sound. detail,soundstage
super-duper,output stage has really big swinging ding-dong er, I mean voltage/current. Not sure Sunfire amp made before 1995. Have you bought the right device? Not Sunn? or Sunbeam? Or even Sunkist?(TAS reviewed late '96 and '99) Please think before speak! :)

Similar Products Used:

Mac, Krell etc.

looks

This is a review for both the stereo and 5-channel Sunfire.
It makes bad sound. It doesn't make music. Low output, lots of hum. I can't go into control, speed, detail, musicality,
presence, soundstaging or layering, because it doesn't do any of those things. Not even if you put an Audio Research
Ref.1 or a Levinson in front of it. Sad but true, move on.

Similar Products Used:

Sim W3, W5, Any Audio Research or Threshold, McIntosh 7200,
McIntosh 7205, 7104, 7106, 7108, CARY CAD 500-T, Sim Audio
HT-5, Parasound 2205, Adcom 7500, Citation, EAD PowerMaster 500 and 1000, Krell KAV-3 and 5, ATI 1505, Musical Fideliy,
Denon, Marantz, and Parasound THX monoblocks, etc, etc..

I have to amend my previous posting! The review I gave was for the 600 WATT STEREO AMPLIFIER - Which is in fact the ONLY "SIGNATURE" VERSION of this Sunfire stereo amp - The standard version is 300 watts per channel as it states above - and it may well sound great in a vertical bi-wire, mono configuration also.

BUT TO ACHIEVE THE RESULTS I EXPERIENCED, BE CERTAIN YOU ARE LISTENING TO THE REAL "SIGNATURE" VERSION!!!! 2x600 WATTS!!!!

Price. Power. Efficiency. Bi-wire and Bi-amping ability.

None in this configuration...

I have owned a single Sunfire stereo signature amp for a few months and had read on the Sunfire website that for a real treat, use TWO of these amps in a BI-WIRE, MONO-BLOCK MODE. Essentially you are using them as mono-blocks, each amp now putting 1200 WATTS INTO 8 OHMS AND 2400 INTO 4 OHMS!!!!!

OH MY G*D!!! WHAT AN AMAZING SOUND!!! TRULY AN AMAZING EXPERIENCE!!

In this configuration, I used them to drive my B&W 802's using a Sunfire Tube preamp and an ARCAM Alpha 9 CD player with Analysis Plus Silver Oval speaker cable.

The sound is remarkable. The music now fills the room with such presence and dynamics that it is like nothing I have ever experienced. It is as if you went from watching a live program on television to being suddenly put in the show, live. The sound is fast, clean, tight and has amazing imaging with each instrument occupying a solid area in the ENORMOUS soundfield. I'm not saying it's like being at a live performance, it just creates such a dynamic and detailed soundstage that the music comes alive in a way that has to be experienced to be believed!

I was so amazed with their performance in this set-up that I had a friend of mine who is a published musician/composer (RICHARD SOUTHER), come over and listen to some of his CD's. He was even more blown away than I was, due to the fact that he has spent hundreds of hours in recording studios, and had heard his music on high end mastering systems, yet he said he had NEVER heard his music sound as amazing as with this set up.

He had heard the same system with just the one Sunfire Signature in regular stereo mode, and had enjoyed it, but he could not believe the difference it made adding the second. We sat and listened with our mouths agape for almost two hours. Afterwards he said the experience inspired him to go back and make more music just to hear it on my gear!!

When you compare the price of two of these amps to just one Krell or other high end/high wattage amp...you can't touch them.

I urge any prospective buyers and all current owners of these amps to try this configuration if you can. YOU WILL BE BLOWN AWAY!!!! I GUARANTEE IT!!!

Just remember to follow the instructions given in the Sunfire manual closely and to keep the volume/gain way down when you start!

I AM GIVING IT 5 STARS IN THIS BI-WIRE, BRIDGED MONO BLOCK CONFIGURATION!!!

I bought a Sunfire used about 6 months ago and find that it really is a good amp for the money, especially if one purchases it used, as i did, for $1200. I agree that it doesn't sound like a tube amp, but it is nice and warm and sounds particularly good in my system which is a Levinson 39 cd player running directly into the amp via Tara Decade balanced interconnects and then powering a pair of Dynaudio Contour 1.3's via Tara Master Generation 2 wires. I found that putting the amp on a pair of cinderblocks and using an old bike innertub partially inflated has increased the bass output considerably and sharpened the soundstage somewhat. It does suck a lot of energy, though, and doesn't have a standby option, which is a drag.