Sunfire Signature Power Amplifier

Sunfire Signature Power Amplifier

Noel T. Keen

5 January 2000


1,200 watts rms per channel into four ohms
4,000 watts one ohm – time limited basis
Frequency response 1 Hz to 80 kHz
Balanced and normal inputs
High quality five way binding posts
Unique high frequency protection circuit
Weight 50 lbs.
Dimensions: 19″ wide, 6.5″ high, 15.75″ deep
Five year parts and labor warranty
Limited production piece hand signed by Bob Carver
List Price: $2,995 US.

Sunfire Corporation
PO Box 1589
Snohomish, Washington 98291
Phone: 425 335 4748
Price: $2995

“I highly recommend the Signature for comparison to anything near its price point, so much so that I bought the review sample as an “affordable” solid state reference!”

Bob Carver is somewhat of a paragon in the high-end since everything he touches turns to gold. After building up and then selling his namesake company, Carver started Sunfire and has produced products ranging from subwoofers to tube preamps that have received acclaim. With this kind of track record, it seemed fitting to review Sunfire’s top of the line stereo power amplifier, the Sunfire Signature.


Following unboxing and set-up on the supplied glass support-plate, the Signature performed flawlessly in my system. Two sets of outputs are supplied, voltage and current related. In my system (normally bi-wired to the Von Schweikert VR-8 speakers) the voltage outputs were sonically superior to the current outputs, with better resolution, presence and weight to the music. The output lugs were rather cheap plastic and two of them failed during my auditioning. Unfortunately, the Signature also comes with a hard-wired power cord, so I could not evaluate various after-marker power cords to the amp. (Publishers note: Sunfire has begun to make all later models, mine being one, with a detachable IEC connector. See my remarks at end of review CP.) No on/off switch is provided the assumption being that the amp remains on all the time. Those few negatives aside, the Signature is well built and finished, with an attractive case and brushed front panel bearing Bob Carver’s signature. A single meter, for reading “power supply energy” serves no useful purpose that I could determine, but does provide esthetics for those who enjoy looking at equipment with such do-dads.

Sunfire uses a switching power supply in the Signature. In addition to supplying leviathan power on demand, it provides one other major practical advantage; namely the amp runs cool, even at high output. Relative to the toasty, class A Krell 600 and KR amps, the Sunfire Sig will return a dividend in lower power bills. It is rather amazing for a cool running and rather light amp such as the Signature to output big power numbers—600 watts per channel into 8 ohms, 1200 watts into 4 ohms and 2400 watts into 2 ohms! Its lightweight and cool running power supplies notwithstanding, this amp can boogie with the big Levinsons and Krells, as we will see below.

I compared the Signature with my reference solid-state amp, the highly rated Krell FPB600 (see my review in the archives of This was of course not particularly fair since the Krell retails for 4x the price of the Signature. Nonetheless, the Krell amp provided a benchmark of comparative quality. I also compared the treble and midrange tonality of the Signature to my reference tube amps, the KR Enterprise VT8000MK monoblocks (at more than 8x the price!). My reference speakers, Von Schweikert VR-8s (96 dB/w/m), were used for most of the listening. However, I still own a pair of Thiel 3.6s, which are less sensitive (87 dB/w/m) and much harder to drive. Accordingly, I used the Thiels in some listening with the Signature. The rest of the system is summarized below.

As indicated above, Sunfire supplies a glass plate to support the amplifier. Naturally, I had to experiment with alternative support strategies and analyze their effect on the sound. Placing the amp on a shelf of the Arcici Suspense stand supported by three #3 Black Diamond Racing cones provided the best sound, but support with #2 Vibrapods on the Arcici stand also yielded an improvement over the supplied glass plate placed on the carpet.


“…the Signature produced a midrange that was well-balanced and uncolored, with good harmonics and resolution. This cannot be said for several price point competitors.”

After several days of burn-in, with generous use of the latest Purist Break in disc, I sat down with the Signature. I was immediately struck by the overall musicality, excellent dynamics and speed of the amplifier. For example, tracks 2 and 3 of the well-recorded MassenetEl Cid Ballet Music (Klavier GCD8002) yielded excellent sound with the dynamics faithfully reproduced. The amp did not seem to impose obvious colorations that I could ascertain. Bass response of the Signature was tight and accurate but it came up short of the Krell amp in overall impact and solidity, not a particular deficit since bass is the Krell forte. The Signature did provide excellent bass power and extension along with finesse on the percussion of track 3 of Thin Red Line (BMG 09026-63382-2).

The crucial midrange was reproduced accurately and without obvious grain through the Signature. The Signature gave neutral tonality on the strings of track 2 of the well-recorded First Impressions MusicClassical Sampler (FIM 006), with excellent hall ambience and air around the strings. On track 9 of Cafe Blue (Premonition PREM-737-2), Patricia Barber’s voice was presented with excellent tonality and fleshed out with generous air and presence. On track 6 of Muddy Waters’ Folk Dancer (Mobile Fidelity UDCD 593), the Signature showed good resolution and detail, with reasonably good horizontal and depth-wise soundstaging. Not surprisingly, the Signature’s mids lacked the liquidity of the KR Enterprise tube amps and the Signature was also somewhat behind the Krell 600 amp in midrange clarity. However, for its price class, the Signature produced a midrange that was well-balanced and uncolored, with good harmonics and resolution. This cannot be said for several price point competitors.

In treble frequencies, the Signature was adequate but not a world-beater. However, the Signature rendered decent treble with good low volume detail on a range of music. For example, tracks of the All Star Percussion Ensemble disc (Golden String GSCD 005) yielded believable and musical bells, cymbals and other percussion, but not with the liquidity and live nature of the KR amps. For a solid state amp at its price point however, I ended up concluding that the treble of the Signature was quite good.

For fun I experimented with the Signature driving the Thiel 3.6 speakers. These hard-to-drive speakers had previously needed more amplification power than a Krell KSA 200S could deliver, a problem that was subsequently solved by the Krell FPB600. Would the Sunfire Signature also drive the Thiels satisfactorily? Based on the highly dynamic, high volume level material thrown at it, the answer is emphatically yes. For example, tracks from the Journey Greatest Hits’CD (Sony CK 44493) were uniformly delivered with great presence and power by the Signature, even at 100 dB plus peak levels through the Thiels. No indications of clipping or lack of composure were heard. It seems that the Sunfire’s lightweight power supply can indeed deliver the goods, as advertised, to power hungry speakers.


Overall, I was positively impressed by the Sunfire Signature amplifier. It performs well in most of the usual evaluation categories, perhaps explaining the fact that the amp is just plain musical. While I could identify particular things the Signature did not do as well as the much more expensive reference amps on hand, musical performance was uniformly high and I did not in any respect feel cheated listening to the Signature. The Sunfire amp performed well with a diverse array of music, ranging from solo flute to heavy rock. Its great power eliminated any fears of “running out of gas” on the heavy stuff. At the same time, the Signature had the uncanny ability to provide excellent detail and resolution to low level music. I highly recommend the Signature for comparison to anything near its price point, so much so that I bought the review sample as an “affordable” solid state reference!

Clement Perry comments:

I too have been listening with, intense appreciation, this smooth beast of an amplifier. I might go even further than Noel. I find its performance, compared to any amplifier at any price, competitive.

There. I said it!

I’ve told this to many audiophiles who otherwise couldn’t believe that a Sunfire amplifier designed by Bob Carver can sound soooo damn good. Being a high ticket, best-design-you-can-think-of type guy, no one was more surprised by the sound of this amp than I. Its performance is virtually flawless compared to the Sim Audio W10 Mono’s that retail for about $10,000. I could not for the life of me find what the W10’s did that would be considered significantly better. They certainly don’t sound two and one/half times, or $7,000 better. On the other hand, the KR amplifiers that Noel continues to refer to as world beaters (at $28,500 they’d better be!), would probably blow up (as my units have three times previous) if they were asked to reproduce a fraction of the power coupled with the extreme finesse Carver’s Sunfire produces. This is not to say that the KR’s don’t produce great sound. They do. Even so, I remain dumbfounded by this Sunfire amp. I’m now listening to only 16/44.1 CD’s to see if those SACD’s are part of the reason behind its exceptional performance. The sound is liquid, detailed, fast, taut, and tight in the low end, and as musical as one could possibly hope for anywhere near the Sunfire’s price. So what we have, dear reader, is an amplifier that in most setups should simply astound regardless of what amplifier you own. As far as I’m concerned, the Sunfire earns no less than the highest praise.

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