Sunfire is the real deal!
If I were to use only two words to describe the sound of a Sunfire amp, I would use openness and clarity. Without a doubt, the Sunfire is among the most open amps I have ever heard when played through a pair of Martin Logan Ascent i loudspeakers. The Sunfire throws a completely unfettered soundstage that's deep, tall, and wide, but not cavernous. There's no hint of strain in this presentation, and imaging is reasonably precise, well-focused, and life-like, especially when vinyl source material is used. The Sunfire also possesses considerable clarity without hyper detail, brightness, harshness, or glare of any kind. The Sunfire is also transparent and detailed; it will reveal weaknesses further up the audio chain the way any reasonably neutral and detailed amp should.
In the Sunfire's Current mode, the music has all the detail, transparency, openness, and clarity that one could possibly hope for from any amp. There is a slight amount of sweetness, warmth, and roundedness to the music that is reminiscent of tubed amplification, but I would not call the sound of the Sunfire tubelike. Many tubed amps I know have a little more texturing, warmth, atmosphere, and less transparency than what the Sunfire provides.
If you like classical music, jazz, and classic rock 'n' roll, you will like the Sunfire/Logan combination. If you like jaw-cracking dynamics, sonic-boom-like bass, overly extended highs, and razor-sharp musical definition, the Sunfire may not be the right choice. But in no way does the Sunfire veil any of the important nuances of the music I love most -- jazz and classical.
Using my current Proceed AMP-5 as a counterpoint, the Proceed is warm, rich, full-bodied, reasonably detailed, dynamic, but not overbearing, and reasonably transparent. However, the Proceed seems a little closed in and dark when compared with the Sunfire. More of the music is revealed through the Sunfire, and the Sunfire has considerably more openness and clarity than my Proceed. Yet, some may prefer the Proceed's greater richness despite the loss of some detail and transparency. These attributes can easily be added to the Sunfire by using a tubed preamp like the Music Reference RM-5. Sunfire's own tubed preamp is far too transparent to add much warmth and textured nuance to the sonic mix.
Incidentally, I had a chance to audition the McIntosh MC402 with a pair of Martin Logan Ascent i loudspeakers at Magnolia HiFi in Seattle last summer. The other components auditioned included the McIntosh MC46 preamp, McIntosh MCD205 CD player, Audioquest Jaguar interconnects with RCA termination, and Audioquest Gibraltar speaker cables. The CDs that I used included “Art Pepper Meets the Rhythm Section” (Contemporary Stereo S7532, 20-bit K2 edition), “Sarah Brightman: Time to Say Good-bye” (Angel CDC 56511), and Mozart Symphony Nos. 40 and 41 performed by the Chicago Symphony Orchestra and conducted by James Levine (Red Seal Digital RCD14413).
I found the MC402 warm, lush, and rich with an enveloping bottom end and a tipped-up treble that not only spot lit that region but added a rich glow to cymbals and bells that was not completely accurate no matter how seductive it might have been. I also found soundstage width compressed at the expense of soundstage depth, which seemed deeper than normal. Detail, transparency, clarity, and openness were not up to the standards set by the Sunfire Signature 600 – Two, which I had heard the day before.
If you cherish traditional audiophile values of neutrality, balance, clarity, detail, transparency, and openness, you may find that the MC402 will definitely have a sound of its own -- a warm, romanticized presentation -- that will only be exacerbated if it is paired with warm-sounding loudspeakers. If you like that type of sound, then you may enjoy the MC402. If you don't, then the Sunfire is definitely the right amp for you.