Finding a good power amp is hard. I should know. I’ve tried a half dozen or so over the past few years from manufacturers such as Classé, ATC, NAD, and Emotiva. All have been sold or returned.
It’s not that all of them have been putrid. A few impressed me. But none made me feel like I needed to hold onto it.
My current speaker setup is nearfield. Usually, I have two sets of speakers that I toggle between. One is always my beloved KEF Reference 1s. Most recently, the other has been a pair of the Philharmonic BMR Monitors — an unbelievable bargain buy. They’re driven by my Schiit Ragnarok 1, which I’ve never been able to displace, no matter how many times I’ve tried. It’s unique, microprocessor-equipped topology is just so darn transparent that it’s been difficult to find something that’s as revealing, deep, and tonally correct as the “Raggy.”
That said, the Raggy is just 100 watts per channel into 4 ohms, and my KEFs have a modest sensitivity of 85 dB. Sitting just a few feet away from the speakers, that’s sufficient. But in the true audiophile spirit, I couldn’t shake the feeling that “moar” power would be better. That led me down the power amp path.
Yet, every destination has been unsatisfying. Whether using the Raggy as the power amp’s preamp, a volume-adjustable DAC as the preamp, or as separate passive preamp, none of the power amps I auditioned could match the Raggy on its own. One came very close, though. The ATC P1 (U.S. MSRP $3,749) gripped the KEFs’ woofers with more authority than the Raggy can, thanks to its copious power. It also was smoother than the Raggy. That said, it projected a flatter soundstage. Ultimately, its mixed blessings just weren’t enough to justify keeping it.
That doesn’t mean I was ready to retire my power amp search. The ATC showed me the potential benefits of a good power amp, even if it wasn’t the right choice for me.
Three that have sat near the top of my “To Audition” list are the Benchmark AHB2, the Cambridge Audio Edge W, and the Bryston 4B Cubed. All are excellent measuring amps that have received praise from other reviewers, but they’re different in just about every other way:
- The Benchmark has a U.S. MSRP of $2,999. The Cambridge has U.S. MSRP of $4,000. The Bryston comes in at a U.S. MSRP of $6,795.
- The Benchmark comes with a one-year warranty for the original purchaser, extendable to five years in the U.S. and Canada (and two years elsewhere) with registration. The Cambridge comes with a two-year transferrable warranty, extendable to five years with registration. The Bryston comes with a whopping 20-year transferrable warranty.
- The (non-rackmount) Benchmark is a diminutive 13 pounds and approximately 11 by 9.5 by 4 inches (W x D x H). The Cambridge weighs in at 52 pounds and has dimensions of 18 by 16 by 6 inches. Only slightly less hulking is the (non-rackmount, handle-less consumer version of the) Bryston, which weighs 42 pounds and measures approximately 17 by 15 by 6.5 inches.
- The Benchmark is a THX-AAA Class AB amp, which in practice means it combines features of Class AB and Class H. The Cambridge is Class XD, which essentially describes a Class AB amp that extends the amp’s Class A range while lowering distortion. The Bryston is Class AB2, which, as Bryston’s James Tanner explained to me, “means that the output transistors overlap a lot between the positive and negative wave cycles to eliminate any crossover notch distortion.” (If one’s looking for a commonality in these three amp’s topologies, it’s that all three seek to minimize a Class AB design’s crossover distortion.)
- In terms of power, the Benchmark is rated at 190 watts into 4 ohms and 100 watts into 8 ohms (when used in stereo, rather than bridged, mode). The Cambridge is rated at 200 watts into 4 ohms and 100 watts into 8 ohms. Finally, the Bryston is rated at a massive 500 watts into 4 ohms and 300 watts into 8 ohms.
- Turning to specs, the Benchmark gives us approximately .0001 THD+N at 100 watts into 4 ohms balanced, the Cambridge produces approximately .001 THD+N at 100 watts into 4 ohms balanced, and the Bryston lands at approximately .003 at 100 watts into 4 ohms balanced. (These results are from the independent measurements linked above.) While both the Benchmark and Cambridge have reached their THD+N nadir at 100 watts into 4 ohms, the Bryston improves until it hits 500 watts. That said, it’s unlikely that any of these amps is producing distortion that’s going to be audible under any realistic circumstances.
All three amps arrived well-packaged, but the Cambridge deserves special mention here. I’ve never encountered a product more expertly packaged than the Edge W. I don’t know if there are awards for packaging design, but if there are, the Edge W deserves them all. The Edge W arrived in an outer box with two clip-on plastic handles on each side. The lid off this box lifts off (after removing the tape, of course) to reveal a generous custom-molded foam sarcophagus for the Edge W. Removing the top of this foam reveals a windbreaker-like cover that encases the Edge W and the bottom piece of foam. The top of this windbreaker needs to be unzipped — yes, there’s a zipper on the packaging! — to reveal the Edge W and its accessories. (For you ‘90s kids, Cambridge basically created a Starter jacket, complete with the Cambridge logo, for the Edge W.) Taken together, the Cambridge’s package gave the impression that it could survive reentry to Earth after being dropped from the shuttle of whichever billionaire makes a vanity trip to “space” next. (To get a sense of just how impressive the Edge W’s packaging is, please check out Tom Tam’s unboxing video. It needs to be seen to be believed.)
Setups for the three amps were relatively straightforward. All three units have switches that all them to be operated in stereo or bridged mono. (For this review, all were used in stereo.) Unsurprisingly, all three also have sturdy speaker terminals befitting their price range. Beyond those commonalities, the units differ.
Both the Cambridge and Bryston offer balanced and single-ended inputs, while the comparatively diminutive Benchmark features only balanced inputs. However, the Benchmark adds mono and stereo NL4 SpeakON speaker outputs. The pro-oriented Bryston and Benchmark label their channels by number, while the more consumer-oriented Cambridge sticks with “right” and “left.” Showing that Cambridge’s attention to detail extends beyond the packaging, the Edge W’s labels are printed both right-side-up and upside-down, making it easy to hook up from behind or in front of the unit. Interestingly, the Edge W also includes both XLR and RCA outputs for each channel. In this reviewer’s opinion, this is a nice addition to any power amp, because it makes it easy for those with a preamp that lacks extra outputs to feed a subwoofer.
Where it comes to gain, though, the Cambridge falls behind its more pro-oriented competitors. Its gain is fixed, while the Bryston offers two-position gain switch and the Benchmark offers a three-position gain (sensitivity) switch. In practice, the noise floor of all three amps was vanishingly low. Even in my nearfield setup, I had to put my ear near the speakers’ tweeters with the preamp’s volume at max to hear hiss. That said, the adjustable gain on the Bryston and Benchmark made it easier to maximize each amp’s signal-to-noise ratio.
The professional orientation of the Bryston and Benchmark comes through on the front of the units, too. While all three can be powered on from the front (thankfully), the Cambridge features only a power status LED. The Bryston and Bechmark, in contrast, both indicate clipping and thermal protection—the former by color-changing LEDs, the latter by separate LEDs.
Speaking of power, each amp did a nice job of starting softly. None produces an excessive thump when powering on or off, with the Benchmark being quietest in this regard.
So, how do they sound?
For these auditions, I tried several DACs, including my own Crane Song Solaris and Matrix X-Sabre Pro and (at Benchmark’s request) a loaned Benchmark DAC3. For DACs with preamp capability, I tried both linking directly to each power amp and feeding each DACs’ fixed output through the superb Benchmark HPA4 headphone/preamp (which will be reviewed separately at a later date). As mentioned above, I tried each amp with both KEF Reference 1 and Philharmonic BMR Monitor speakers. For the AHB2, I tried both traditional speaker cables and the SpeakON outputs. While each DAC imparted its own character, I otherwise didn’t discern many significant differences in each amp’s performance between the above setups. Ultimately, I found that using each DAC’s fixed output into the HPA4 to be the best way to audition the speakers, since the HPA4’s optical volume control made it easy to match the output levels of each amp using an audio interface and Room EQ Wizard.
When reviewing DACs or evaluating versions of albums, I like to have the ability to switch quickly between level-matched sources. That isn’t really possible with power amps. So once I determined the proper volume setting for each amp on the HPA4 to match their levels, I hooked up one amp, adjusted the volume, and ran through a selection of songs as I took notes. Then I switched the amp, adjusted the volume, and repeated the process. Ultimately, I went through dozens of rounds across several listening sessions spread over several months. I didn’t consult my previous notes, starting from scratch each time. While audition material occasionally revealed something new, my impressions of the amps were remarkably stable across time.
For parsimony’s sake, let’s zero in on three audiophile-worth recordings that I think illustrate the differences between each amp.
It will come as no surprise to loyal Audiophile Style readers, that my first audition track comes from Van Morrison’s collection of rarities and outtakes, The Philosopher’s Stone. “The Street Only Knew Your Name” was recorded live in the studio at The Record Plant Sausalito in 1975. It’s a superbly natural recording, which provides a well-defined sense of the studio space. The snappy honk of John Blakey’s guitar intro in the left channel reverberates into the right before the rest of the band, highlighted by David Haynes burbling bass, kicks in. As I’ve mentioned in previous reviews, there’s a shaker in the center-left channel that enters after the guitar intro and propels the songs forward. Through good equipment, one can identify each individual pebble in the shaker, which is almost three-dimensional and placed behind Blakey’s guitar, Morrison’s voice, and the backing vocals, but in front of Tony Day’s drums. On less discerning equipment, the shaker becomes a nondescript “shh-shh” sound that’s harder to place in the mix. Likewise, on gear with good front-to-back layering, Morrison’s sax solos should sound like they’re emanating from just behind his voice.
Pitting the Benchmark and Cambridge amps against each other on “Street,” the differences in depth and bass authority were apparent. The AHB2 provided a smidge more air than the Edge W. The latter’s soundstage seemed flatter than the Benchmark’s, creating less of a sense of the recording space. Both Morrison’s voice and horn parts seemed to be pulled towards the front through the Cambridge. Overall, the Benchmark simply seemed to wring more detail out of the recording, even if the differences were subtle. Both amps passed the shaker test, but only the AHB2 layered correctly. That said, despite nearly identical power ratings, the Edge W offered a more substantial low end, even if it wasn’t quite as clean sounding as the AHB2’s bass.
Throwing my trusty Ragnarok 1 against the AHB2 and Edge W, the power amps acquitted themselves well. This wasn’t, in other words, a simple case of sticking with my Raggy and moving on. The AHB2 came closest to the Raggy’s depth and natural tone, even if I wasn’t quite sure it made it all the way there. But the ABH2 did seem ever-so-slightly more detailed than the Raggy while reducing the latter’s sometimes aggressive-sounding top end. Yet, despite both the AHB2 and Edge W boasting more power than the Raggy, only the Edge W seemed to grip the speakers with an authority that surpassed the Raggy’s.
Thus far, the refrain that differences between well-designed amplifiers tend to be small rang true. But adding the Bryston 4B Cubed to the mix upended my perception of what can be expected from an amplifier.
The differences between the Bryston and the other amps seemed so significant that I had to run through my level matching a few more times to make sure I hadn’t made a mistake. The 4B Cubed provided it all: depth, detail, authority, accuracy, and smoothness. With no exaggeration, I’d never heard “Street” sound so good through speakers.
As Blakey’s guitar intro ended and the band rhythm crashed in, I was gobsmacked by the Bryston’s effortless dynamics. Yes, all that extra power matters. But it wouldn’t have mattered that much if the Bryston didn’t also pass the shaker test with aplomb, matching the ABH2’s clarity and then some. Haynes’s bass was both thumping and clean. Where the Bryston really excelled, though, was its staging. It’s combination of width and depth imparts an almost wraparound sonic image. Among other things, this made relatively minor differences in each of the upstream DACs’ depth much easier to spot. Finally, I could detect nary a hint of grain or glare anywhere in the Bryston’s reproduction of “Street.”
Turning to other well-worn audition tracks, I was anxious to see if the Bryston could continue to deliver and how the other amps would fare in comparison.
One can scarcely have an audiophile equipment showdown without some Steely Dan. So I turned to “Haitian Divorce,” written about the Dan’s legendary engineer Elliot Scheiner, from the 2018 Japanese mastering of The Royal Scam, an excellent flat transfer of the master tape marred only by the fact that it’s only available on the inferior and unfortunate UHQ (a.k.a. MQA) CD format.
Powered by the Benchmark, legendary drummer Bernard Purdie’s languidly funky kick/snare combination stages deep in the mix without losing any clarity. Throughout the track, “clarity” was the watchword for the AHB2. The Benchmark made it easy to separate Donald Fagen’s double-tracked vocals, and every overtone of Chuck Rainey’s bass comes through unmuddied.
Flipping to the Cambridge, the same general differences that were apparent on “The Street Only Knew Your Name” were there but were much more muted. Yes, the Edge W staged Purdie’s drums slightly closer than the AHB2 did, but the difference was minor. This time the Edge W kept its…err…edge over the Benchmark when it came to bass authority while giving up very little ground in the transparency department. Moreover, it now seemed clear that the Cambridge was projecting a taller soundstage than the ABH2 was, a characteristic that I often associate with ample, clean low end.
If “Haitian Divorce” evened the score between the AHB2 and the Edge W, the 4B Cubed went out of its way to demonstrate that its superlative performance is agnostic when it comes to audition material. From the first staccato piano chords, the Bryston’s enveloping soundstage was back in full force. Purdie’s aforementioned drums were more-three dimensional through the 4B Cubed, set further back in the mix without losing any immediacy. They hit harder, too. Perhaps most importantly, subtleties like the synth horns in the right channel at the 1:40 mark of “Haitian Divorce” had more realism and texture through the Bryston.
The final track in my formal audition was “Political World,” the opening cut from Bob Dylan’s 1981 classic Oh Mercy. The combination of producer Daniel Lanois and engineers Malcomn Burn and Mark Howard gave Dylan one of his most audiophile-worthy albums, and MoFi’s Rob LoVerde and Shawn R. Britton brought out the best in the recording in their 2019 mastering.
Pitting the Benchmark and Cambridge against each other on “Political World,” the AHB2 takes the lead again. The string articulation on Lanois’s Dobro in the left channel is easier to make out through the Benchmark than the Edge W. Likewise, the layers of complex electric guitar work are more with the AHB2. While its soundstage is shallower than the Cambridge’s, it’s also more coherent. Through the Edge W, Dylan’s voice is set deep in the mix, while everything else is pulled to the font, creating an odd sonic picture. Overall, the Edge W makes “Political World” sound muddier, with much of the high end having a slightly muted quality. These differences are small, but they’re real.
Bringing the Bryston back into the comparison, I was startled by just how much harder the track’s low end hits through it compared to either the Edge W or the AHB2. However, this added bass girth didn’t mar the nuances of Tony Hall’s bass — or any other instrument, for that matter. The 4B Cubed placed everything where it should be in a sonic picture that was both deeper and wider than either of the other amps under consideration, yet without any of the disconnection between instruments noticeable on the Edge W. Even more so than on the other tracks, “Political World” underscored the way the 4B Cubed made both pairs of speakers sound larger. Through the 4B Cubed, it was easy to locate all of the instruments in the soundstage, but it was hard to locate the speakers as the source of the sound. The Bryston, in other words, provided that ineffable sense of realism that audiophiles crave.
All told, what did I learn from this comparison?
The overarching lesson for me was that there are, in fact, several power amplifiers out there that can offer the Raggy’s tonal accuracy and delicate transparency.
Based on my time with the ATC P1, I knew that some existed. However, the ATC also showed me that the Raggy’s reproduction of depth was harder to find.
So, if the ATC couldn’t displace the Raggy, could the AHB2 or the Edge W?
I’m not so sure.
The ABH2 offers the kind of just-the-facts transparency I gravitate towards. It also comes closest to the Raggy’s front-to-back staging, though it doesn’t get all the way there. It also doesn’t provide any more power than the Raggy and sometimes suggests a touch of glare or grain the treble, albeit less so than the Raggy. The Edge W offers a smoother listen than the AHB2. Despite having similar power specs to the AHB2 on paper, it’s also the more commanding amplifier. More practically, the Edge W includes the most convenient input and output options I’ve ever encountered on a power amp. However, the Edge W sounds neither as smooth nor as powerful as the ATC, even if it does reproduce depth a little better.
Ultimately, were I considering only the ABH2 and Edge W as replacements for the Raggy, I don’t think either could provide the knockout blow, particularly given their price tags relative to the Raggy’s.
The answer is quite different for the Bryston. The 4B Cubed is so head-and-shoulders above the Raggy and its other competitors that it approaches a cost-be-damned Delta. With the single exception of inputs-and-outputs, there’s no category that the Bryston doesn’t handily best all competitors. It doesn’t just sound better than the Raggy in a few ways. It supersedes it in every sonic category, and by a substantial margin.
In other words, I’ve found my new amplifier.
Model: 4B Cubed
More Info: 4B Cubed Product Page
More Info: AHB2 Product Page
Manufacturer: Cambridge Audio
Model: Edge W
More Info: Edge W Product Page