From the stables of Underwood Hi-Fi comes another thoroughbred contender: the new Emerald
Physics 600.2SE stereo amplifier. And let me tell you, this one’s a real beast. Claimed to drive essentially any speaker providing any load, this balls-out amp is capable of up to 600 watts per channel at full power into 8 ohms. Yeah, that’s nuts; I’ve never seriously contemplated having that much power at my fingertips before, well, at least in my listening room.
Words and Photos by John Richardson
When Marc Phillips contacted me to see if I had any interest in reviewing the piece, my first thought went to my ATC SCM 100 monitor speakers. These are quite large physically, and they can sound accordingly so. The ATCs are actually quite efficient (at least by ATC standards), but everyone says that all ATC speakers love power, and lots of it. Here, I thought, might just be the ultimate test to allow me to get to the bottom of this audio urban myth. Bring on the horsepower!
The SCM 100 monitors are also by design ruthlessly revealing. They sound fantastic in terms of timbre, dynamics, and sheer scale, but they also suffer no fools when it comes to the amplification driving them. I’ve gotten great (but different) sound out of them when driven by low-powered solid state (e.g., First Watt), high-powered solid state (e.g., Pass Labs), and even tubes (e.g., McGary Audio). Maybe, but maybe, the Emerald Physics amp might just be the ticket to get these monitors to really sing as they’ve never sung before.
I sure was keen to find out…
Emerald Physics 600.2SE Specifics
Once I gave the thumbs-up to Marc on the review, arrangements were deftly and efficiently made by my old buddy Bill Leebens, who apparently functions as Underwood’s head press guy. In short, I had the 600.2SE on my doorstep in practically no time (thanks Bill!).
Upon un-boxing I was taken somewhat aback at how lightweight the amp is. Chalk up one practical advantage of Class D. As much as I adore my Pass Labs X250.8 amp, the thing is a bitch to move. Knowing its sheer mass and eyeing those prickly heat sinks always puts me a bit on edge. I usually keep the amp on a wooden platform on the floor, which I push around the room as needed. No use in straining my 56 year-old back, you know.
Not so the Emerald Physics amp; I could easily pick it up and move it around as if it were a sack of groceries. Checking the specs, I found that the amp comes in at a quite manageable 15 lbs. As I stated before, the 600.2SE does 600 watts per channel into 8 ohms, and up to 750 watts into 4-ohm speaker loads. All of this grunt is courtesy of the ICE power 1200AS2 power core, a tried and proven denizen of the class D amplifier world.
Thinking on all of this, I decided to do a bit of mental math: while the Pass Labs X250.8 provides 2 watts per lb (per channel), the Emerald Physics 600.2SE offers up an astounding 40 watts per lb! I’m not sure these metrics have any meaning beyond portability, but they do say something regarding the differences in design between more traditional Class AB amps and the newer breed of Class D amps.
So much for pure power.
What else does the Emerald Physics 600.2SE amp have going for it? Well, there’s one big thing: a vacuum tube input buffer. Termed the hyper SET hybrid valve buffer, this device makes use of a pair of E88CC tubes operated in a single-ended configuration to give the amp that touch of sweetness we audiophiles love to hear (and talk about). Don’t want that? No problem, the tube buffer can be switched out via a toggle switch on the front panel. I personally had no desire to switch it out, and I doubt that you would either.
As far as other sundry items go, the 600.2SE amp sports both RCA and XLR inputs, as well as a pair of very nice binding posts offering output signal to your speakers. The bead-blasted casework seems substantial and attractive, befitting the price point of the amp. I also appreciated the analog VU meters on the front panel, which glow in a mellow orange (pumpkin spice latte, anyone?). These track the power output of the amp if one were to really care. Hey, but they are cool!
Diagonal venting is cut into the top plate, which allows a fun green pattern to be projected onto the ceiling of my listening room while the amp is on. The one thing I didn’t like, however, was the power-on LED. This thing glows like a halogen headlamp on a car and about drove me crazy, whether I was forced to view it directly or peripherally. Note to Underwood Wally: tone the bugger down or eliminate it altogether.
Power-up is sequential out of standby, with the tubes heated prior to fire-up, followed by ignition
of the ICE power module, which happens with a barely audible “thump.” According to the folks at Underwood Hi-Fi, the Emerald Physics 600.2SE was designed in the USA and is manufactured in China. That said, overall fit ’n’ finish seemed quite nice for the price point. I found it to be an attractive piece in an elegant but utilitarian sort of way.
Sonic Impressions
The first thing that jumped up and grabbed me as soon as I hooked the Emerald Physics 600.2SE up to my ATC monitors was how huge the sound coming out of those boxes was! Much like an idling muscle car, I could keenly sense the sheer power under the hood, just waiting to be let loose on humanity.
To be sure, I’ve never quite trusted class D amplification employing high-frequency switching power supplies. I have no logical reason for my reaction, other than that the technology isn’t exactly traditional in the mainstream of perfectionist audio. It’s weird, as I’ve personally had some very positive experiences with class D, ranging from the tiny Tripath (class T) amps up to a pair of Merrill Audio Thor mono blocks which I used as my reference amps for a couple of years. Contrary to what the naysayers say, class D doesn’t have to sound steely and un-engaging; in fact, when properly implemented, it sounds nothing like that. Well-done class D sounds accurate, dynamic, tonally correct, and eminently engaging.
Fortunately for Emerald Physics and Underwood Hi-Fi, the 600.2SE seems like Class D done right. As mentioned earlier, the ICE power modules are well-vetted and highly regarded in the industry. I also believe that coaxing the most out of such devices depends on the design and implementation of the ancillary circuitry and high-frequency filtering, much like the sound of a DAC depends on the analog circuitry coupled to the DAC chip.
So back to my impressions.
The power was there; but really what grabbed me was the sheer delicacy and touch the Emerald Physics amp imbued upon the musical presentation. Through the Bricasti M1 Special Edition DAC and SPL Elector preamp, the tunes flowed out of the 600.2SE/ATC amp and speaker combo like a dam bursting, but with unexpected finesse.
I heard warm harmonics, but with more than sufficient detail to let me peer deep inside the musical performance. I got the warm, pleasing midrange presentation that I know the ATC speakers of capable of when properly driven. And treble was pleasing and extended, but never over-the-top steely or etched.
Up the volume went, and try as I could, I just couldn’t get the Emerald Physics 600.2SE to waver. As I did so, I kept my eye on those VU meters, hoping the needles would dance to my visual pleasure. Alas, it was not to be: no matter how big the orchestral crescendo, the needles barely wavered, much less danced. Apparently, the big ATC monitors were barely tapping into the vast power reserves offered up by the amp. I felt as if I were nosing a Ferrari around a parking lot. Nonetheless, it was comforting to know the power was there. Just in case.
I’ve saved the best for last. The bass through those big 12-inch woofers was spellbinding. Extension and control were top-tier; probably the best I’ve heard my ATC monitors do. It didn’t matter if the bass were of orchestral or electronic origin, it was there.
Bring on the Tunes!
The Emerald Physics 600.2SE just begged me to sit up straight and listen to some serious orchestral stuff. Much as I love my smaller speakers and amps, they just can’t do justice to a full-tilt symphony orchestra strutting its stuff. That’s why I have the big ATCs and amps powerful enough to really drive them; you can count our Emerald Physics beauty among that crowd.
One favorite performance I pulled out of the archives was William Walton, as recorded in stereo on EMI, conducting a slew of his own works. Years ago, I did a high-resolution needle drop on this album, which has since turned out to be something of a reference recording of mine. Part of this compendium includes Walton’s reading of his own “Belshazzar’s Feast,” an extravaganza of vocal and orchestral power (24/96 kHz transcription from vinyl). The recording of this performance captures the full gravity of the orchestra and chorus; one also hears (via a properly resolving system) exquisite layering of the voices and orchestra. I sometimes remember to use the first few minutes of the piece to test the resolution and spatial characteristics of an audio component in my system.
From the sharp, piercing brass in the opening bars to the quiet entrance of the chorus, the system drew my undivided attention. I had no trouble hearing the deep layering of the soundstage, with the orchestra up-front, and the voices fading way back into the soundscape. I also made careful note of the tonal accuracy I was hearing, as the ATC speakers don’t lie. If there’s an issue with either source or amplification, it will be conveyed and heard. Both massed voices and instruments sounded pretty darn real, just as they should in this very natural recording. Nothing sounded overly pretty or romantic, nor was there any tonal harshness or strain. To this end, the Emerald Physics amp breezed through two very important tests at once.
Keeping with the orchestral venue, I realized that having the Emerald Physics 600.2SE amp in-house would provide an excellent opportunity to continue a project I started some time back, but for some reason dropped. This was my exploration of Andris Nelsons’ cycle of Shostakovich’s symphonies with the Boston Symphony Orchestra, captured in superbly dynamic and natural sound by Deutsche Grammophon (DG). There’s little need to wax poetically about Nelsons’ interpretation of the works, or the performances as rendered by the BSO; the quality on both counts is obvious. What really stands out is the reference quality of the recorded sound; any of these recordings could easily stand alone as an audio nut’s dream test track. The sound is natural, dynamic, and highly nuanced. What’s not to love?
Digging into the well-known Shostakovich Symphony #5, I was able to easily enjoy the full majesty of the orchestra: nuanced strings, vivid percussion, and biting brass. Tonality seemed spot-on; the sonority of the solo clarinet in the first movement cut through with stunning clarity. Dynamics were no slouch either, as I felt the full-on impact of orchestra crescendos. And the ATCs sure did play loud without strain or distortion when driven by the Emerald Physics amp. I often had to make sure to turn down the volume to protect my hearing, as I just wanted to keep running the levels up. Even so, it was hard to resist hearing those bass drum salvos at full blast-enough to seemingly break a window or two.
Backing off into some easy jazz, I was more than able to enjoy the subtleties of Charles Lloyd’s album Canto (16/44 kHz flac, streamed via Qobuz). The first cut, “Tales of Rumi,” starts out softly, with strings and gentle percussion, and builds to a hefty climax, with Lloyd’s sax screaming out the tune. The Emerald Physics 600.2SE amp sailed right through, capturing the gentle, intimate nuances at the piece’s front end just as well as the impact of the wailing saxophone toward the end. The delicacy of the tune shone through as if I weren’t listening to a monster amp, but rather a low-powered vacuum tube system with lights off. And that’s a great thing indeed!
Emerald Physics–The Wrap
I must admit that I was more than pleasantly surprised by the overall performance of the Emerald Physics 600.2SE class D amplifier. I knew it would play big and dynamically, and I fully expected it to go deep in the bass while fully controlling the 12-inch woofers on my ATC monitors. What I wasn’t expecting was its ability to flesh out the harmonics in good recording, and delight me with delicate, accurate tonality, regardless of the type of music I played. I require proper tone to fully engage in listening, and the Emerald Physics didn’t disappoint. I’m sure the tube buffer input on the amp didn’t hurt in this regard; what a brilliant addition!
That the Emerald Physics 600.2SE comes in at an introductory price of just $1,999 is a pure gift for what the piece delivers. I’ve heard my share of amps that boast huge power output and that can supposedly drive any speaker in existence. Problem is, they sometimes just don’t sound all that involving. That’s probably why I personally gravitate more toward lower powered amplification as long as I can get away with using it. Well, Underwood Wally might just have made me even more of a believer in the sonic nuances of well-executed, powerful class D amplifiers.
At the price point of the Emerald Physics amp, I can’t really uncover any shortcomings worth
mentioning. It’s really just a great amplifier, and I can’t say enough positive things about it. The fact that it effectively drove the super accurate and resolving $25,000 ATC SCM 100 monitors with such great aplomb and enjoyment on my part speaks volumes in itself. Because of its tremendous value and overall superb performance, I’m unabashedly nominating the Emerald Physics 600.2SE amplifier for a Reviewer’s Choice Award. Another win to Underwood Hi-Fi!
Reading the review, I thought of Magnapan’s. This could be the low cost amp for them.