Musical Fidelity kW Hybrid line preamplifier & kW750 power amplifier Page 2
If anything, the Wilson MAXX2's high-frequency presentation and their ability to express air are somewhat repressed compared to those of some other speakers I've auditioned, yet I never wanted more of anything on top when playing familiar recordings that are particularly spacious and airy. There seemed to be a slight lessening of cymbal shimmer and string pluck compared to the kWp-kW combo, but some regular listeners here think that combo sounds slightly bright and spotlit. Only with a few rock recordings did I wish for more splash and sizzle than the kW and kW750 delivered. Most of the time I found their top natural, fast, extended, and sufficiently airy. Aggressive recordings sounded aggressive, but somewhat dull ones were never suffocated.
Cisco's fabulous reissue of June Cristy's sultry Something Cool (LP, Capitol/Cisco), from 1956, proved the combo to be supple, delicate, and detailed performers. The recording of Cristy's voice is nearly ideal, the former singer with Stan Kenton's big band close-miked and unprocessed. Though it's monophonic, the recording carves out intricate layers of instrumental detail and produces subtle microdynamic gradations of voice and instruments. Cristy was cleanly presented well in front of the musical backdrop with convincing three-dimensional solidity but without being clinically delineated in space. I could easily hear her making small adjustments to her volume and her distance from the microphone. Pete Rugolo's playful, almost campy arrangement of the title tune floated on a velvet cushion, neither strident nor muffled. My recollection was of a bit more edge and perhaps a hint of vocal spotlighting through the kWp and kW. This was better.
While the new combo didn't produce the midrange bloom and airy delicacy of a great tube system, it did float remarkably graceful, effervescent images that never sounded wiry, hard, harsh, thin, or overly analytical, though those preferring a faster, more stiffly tuned presentation might describe the kW750 as being tilted toward the bass, and somewhat sluggish from there up in order to make the sonic picture cohere. Not I—this sort of presentation suits my tastes far better than what I've heard from Mark Levinson, Krell, Halcro, or Theta amps, which tend toward the cool, the analytical, the tight-fisted. Your tastes may be otherwise.
The better tube amps I've heard deliver bass weight and authoritative textures managed by few if any solid-state amps, with speed and control usually taking hits. Most solid-state amps err on the side of precision and tautness while giving up bass weight and depth. The kW and kW750 neatly walked the line between the two, producing believable weight, texture, and control. The Wilson MAXX2's bottom end is the best I've heard from any speaker, especially in terms of extension and control, and in this regard I heard no differences between my MF reference and the new combo. Both drove the MAXX2s' bass bins with spectacular ease and control.
Minimally miked two-channel recordings, such as David Chesky's stupendous-sounding Area 31 (SACD/CD, Chesky SACD288), were slightly more laterally compact than I recollect their sounding through my references. Though my references and the review pair produced equally convincing stage depth from familiar favorites, the former were consistently better able to separate individual images in space—though some would say at the expense of ultimate transparency and image palpability.
Are you lucky enough to own an original stereo "six-eye" pressing of The Sound of Jazz (LP, Columbia CS 8040), a studio recording made the day after a December 8, 1957, live CBS TV broadcast starting veteran and modernist jazz greats including Billie Holiday backed by Mal Waldron, Lester Young, Coleman Hawkins, Ben Webster, Doc Cheatham, and Jo Jones, and a big band led by Count Basie including many of the above? If so, you'll love hearing it through these electronics. Through the Wilson MAXX2s, this fabulous 30th Street Studios recording arrays the musicians dramatically in a great U-shaped soundstage. The sound is imbued with that convincing breath of life: the brass sound metallic yet feathery, as you hear live; woodwinds sound reedy, yet with an overall mellowness. The midband delivered by the hybrid kW and solid-state kW750 was fully fleshed out, almost tubelike, with a complete absence of etch, grain, or harshness—but again, I've heard other amps stretch the "ether" out of which this musical activity emanates more tightly, yielding a faster, more agile presentation.
My overall impression of the combination of the kW and kW750 was of a rich, buttery musical presentation that was not at all smothered or starved on top for air or transient speed. I can't imagine anyone not responding enthusiastically to the pair's overall performance, though those seeking a faster, tighter, somewhat brighter, more damped sound might not respond as enthusiastically.
My sense was that anything much faster and tighter than the kW and kW750 would sound less like live music and more like "hi-fi," but I'm sure different speakers and source components would yield different results. But needless to say, with 750Wpc on tap—and given Musical Fidelity's admirable track record of meeting published specs, I don't doubt that claim—the dynamic range was limitless, and the kW–kW750's effortless presentation almost matched that of the even more powerful kWp-kW's.
kW Hybrid Line Stage out
To sort out the contributions made individually by the kW and kW750, I needed to remove them one at a time. Having the Manley Labs Steelhead phono preamp ($7300), which has a volume control and a line-level input, made getting the kW line stage out of the way easy: I ran Musical Fidelity's kW SACD player into the Manley and ran the Manley's variable output directly to the kW750. Now, only its volume control separated the Manley's circuitry from the amplifier. With the kW Hybrid line stage out of the circuit, previously played LPs sounded somewhat different, but, much to the kW's credit, not dramatically so—especially in terms of all-important transparency.
The biggest differences were at the very top and bottom. The bass became somewhat more supple, though, surprisingly, attacks seemed slightly softer and less assured. The upper mids to highs seemed ever so slightly more recessed yet more graceful and delicate, and transients lost a bit of edge. Whatever the differences, they were so minor that, after I'd listened to the system for a few minutes, with and without the kW Hybrid, they quickly fell between the sonic cracks and were lost; I'm not sure which presentation was "better" or more accurate. Whether these differences improved or hurt the final picture will surely depend on the associated gear—that's how essentially transparent and colorless the kW was. If you want your preamp to add "soul" or sprinkle "magic dust" on your system, the kW won't do it.
Switching to digital through the Manley's Line In input yielded more of a difference. While the Steelhead's signal/noise ratio is impressive for a tube product and I didn't hear its higher noise floor as noise per se, it can't match the kW's dead-quiet backgrounds. Playing pure DSD recordings, I noted (or imagined) a slight loss of low-level dynamics when I bypassed the kW and ran the SACD player through the tubed gain stage. And while I preferred SACD/CD through the kW Hybrid line stage, the Manley Steelhead's impressive performance (add Manley's $900 Skipjack line-stage switcher to increase input choices) was something potential buyers ought to consider when factoring in its high price ($7300).
Next I inserted my reference, two-box kWp preamp, which cost $12,000 compared to the kW's $4500. While I can't say it was more than twice as good, the kWp took my system to a new level—especially spatially. Whether the "improvements" were additive distortions or the result of the kWp's ability to pass the signal with greater transparency while driving the amplifier more effectively, only an oracle or an overstuffed know-it-all audio reviewer can say with confidence. I can say that in my system the kWp produced a somewhat more expansive soundstage, extending its dimensions in all directions and adding or revealing more air and shimmer to the upper octaves, as well as seemingly finer gradations of attack and decay. (This was perhaps partly due to the kWp's greater channel separation, though for analog, >84dB is more than enough.) It added a level of musical and sonic excitement I wasn't expecting, given my long-term listening satisfaction with the kW Hybrid. That said, the newer combo still sounded somewhat more mellow than the kWp-kW combo.
Finally, after months with the kW750, I once again fired up the 1000Wpc, three-box kW amplifier (and yes, I dutifully switched back to the kW line stage, then replaced it with the Manley). Before doing so, I spent a few days listening to large-scale symphonic works. Recordings with wide dynamic swings might let me know if 250 additional watts per channel—more than most amplifiers deliver to begin with—could possibly produce greater dynamic scaling. The kW750 was already loafing along, laughing at the most dynamic DSD recordings I could throw at it. Yet when I inserted the big monsters and their 1.5dB of additional dynamic headroom, the picture seemed to open up yet again, producing an even greater sense of overall sonic ease while delivering even more prodigious macrodynamic bangs.
I'm talking about performance at the outer edges here—performance that requires big speakers capable of playing very loud and handling enormous amounts of power, such as the Wilson MAXX2. But more than ever, I'm convinced that if you want to reproduce in your home a concert-hall dynamic reality that is liberated from sonic strain and hints of congestion, you'll need more power than you think. That said, as promised by Antony Michaelson, the kW's upper octaves were not as smooth and refined as those of the lower-powered kW750; I noticed a bit of edge and etch.
When I again played my six-eye The Sound of Jazz, its slightly U-shaped stage was replaced by a flatter, airier, wider one on which slightly brighter instruments appeared, better defined in space. Billie Holiday's voice sounded less convincing and more strident than through the kW750. However, both of these big amps continued to be models of upper-octave refinement compared to some other big solid-state amps I've heard. Some of the latter have sounded soft, overly polite and too refined, losing detail and resolution in the process. Others have sounded etchy, harsh, and astringent even as they resolved more information.
I have not heard every one of the great high-powered amplifiers out there, and there may be some that do all this better. But pitted against the demands of live music, the limited-edition kW ($27,995) struck a great balance among sonic voluptuousness, high resolution, and the power needed to deliver the full measure of dynamic goods without strain. The new, far less expensive kW750 ($10,000) offered even greater sonic refinement in the upper octaves without giving up much in the way of detail, and while the kW750 isn't as powerful as the world's most powerful amplifier, the mighty kW, it's more powerful than anything else out there that I can think of. I expect the kW to be the last amplifier I will ever buy. If you plunk down $10k for a kW750, you should expect that it will be the last amplifier you buy. Unless you're an inveterate equipment churner (you know who we are), more than likely it will be. It's that good.
The kW Hybrid Line Stage is an easy call. Overloading it would seem to be impossible. It's as quiet a preamp as I've heard, and whatever changes it made to the music fed it were so minor as to be inconsequential. Operationally, it was flawless.
As for the kW750, back in August I attended and participated in a two-day open house at Seattle's Definitive Audio. It was a great chance to meet with subscribers and encourage the rest to start reading Stereophile. The timing couldn't have been better: the store was hosting Wilson Audio, B&W, Classé, Halcro, Musical Fidelity, and Transparent Audio, and my review of Wilson's MAXX2 was the cover story of the issue of Stereophile then current.
One of Definitive Audio's sound rooms included the Wilson MAXX2s and the Musical Fidelity kW and kW750—essentially what I was listening to at home. Another room was reserved for a B&W-Classé system, while a third housed another pair of MAXX2s in front driven by big Halcro monoblocks, and a pair of WATT/Puppy 7s in the rear. Surround-sound source material was provided by Wilson's Peter McGrath, a renowned classical-music recording engineer. Each 45-minute listening session was followed by a 15-minute break so that guests attending each evening's four-hour event could hear all three rooms.
There were no surprises: the Wilson–Musical Fidelity combo sounded remarkably similar to what I heard from it at home. What surprised and instructed me—and, I'm sure, those in attendance—was how different those three rooms, each filled with expensive and highly regarded equipment, sounded.
It was no surprise that the two pairs of MAXX2s sounded very different from the new B&W 802Ds with diamond tweeter. What surprised me was how different the MAXX2s sounded, in one room driven by the Musical Fidelity kW750, in the other by a pair of far more expensive, ultra-low-distortion but less powerful Halcro amps. At the end of the second day, after listening to a spectacular recording of Mussorgsky's Pictures at an Exhibition Peter McGrath had recorded in surround sound, I got him to play some of the CDs I'd brought along and had listened to throughout the event. (I brought LPs too, and some of the CD-Rs were sourced from vinyl.)
The rooms were not identical, but were close enough for me to be pretty sure that the differences I heard between the two pairs of MAXX2s were based on the amplifiers driving them. The Halcros produced a faster, tighter sound, with a spotlit soundstage on which even the most minute macrodynamic and spatial details were revealed with bristling energy, but I found the upper midrange and above dry and overly analytical. The bass was tighter yet lighter, though with more punch, and with less weight, texture, and tactile impact. I can understand why such a sound appeals to many music lovers, but to my ears the kW750 sounded richer and more attractive overall, with a sweetness, transparency, and depth more akin to what tubes deliver.
Two entirely different presentations of the same source material and by the same loudspeakers—which was "correct"? Neither, of course. We're talking about recorded music and the illusion of re-creating the live event. Depending on your tastes, and where your ear and brain gravitate to to "sell" the illusion of live, you will prefer one or the other presentation. For my musical and sonic tastes, and compared to what I regularly hear when seated in Row 20 of the somewhat bright Avery Fisher Hall, I'd go for the more powerful, far less expensive, and somewhat less detailed kW750.