Esoteric RZ-1 Integrated Music System (TAS 209)

Equipment report
Disc players
Esoteric RZ-1
Esoteric RZ-1 Integrated Music System (TAS 209)

Modesty is not an approach that earns high marks in the high end. Pleasing hobbyists with limited room to spare is not usually on the to-do list. Take the once-conservative integrated amplifier. In many instances, even it has grown to Brobdingnagian proportions—the Plinius Hiato or Pass Labs INT-150, for examples. As for the diminutive all-in-one component, such as an integrated amp/CD player combo, the look you might expect to get from a fellow audiophile is pitying at best.

These were my thoughts when I first saw the Esoteric RZ-1—a potent but petite chunk of gleaming aluminum that Esoteric calls “an integrated music system for casual listening.” That’s right. It’s an ultra-compact integrated amp and disc player. From Esoteric? You mean the A-100, P-03/D-03, G-0Rb Rubidium Master Clock Esoteric? Yep, that Esoteric. I don’t know about you but when I think “casual,” I’m thinking clock radio, which set me to wondering what Esoteric was thinking. Leveraging the reputation of high-performance luxury products is an old game in every marketplace segment. It’s the hi-fi version of the automotive world’s classic “Race on Sunday, sell on Monday” mindset.

So what was Esoteric thinking? A lot, actually. The RZ-1 is a CD and high-resolution SACD player coupled with a 100Wpc integrated amplifier augmented with a USB DAC and—wait for it—a moving-magnet-compatible phonostage. To my knowledge there is no other single-chassis component that bridges so many divides. A spitting image of Esoteric’s own AZ-1 integrated amp with a couple of knobs missing, the RZ-1’s casework is streamlined and curvaceous. But it’s the rigid jewelry-like aluminum construction topped off with a 40mm front plate that grabs your attention. Esoteric proudly points out that a total of eight hours is needed to three-dimensionally process the aluminum—all with one-micrometer precision.

There’s nothing casual about the topology either. The RZ-1 amp is a hybrid design equipped with a powerful analog power supply circuit coupled to a Class D switching output stage. Esoteric states it used the largest toroidal transformer that could be stuffed within the slim housing; the hefty capacitors were also the largest possible. They do seem to take up the lion’s share of the interior. Nonetheless, speaker matching is important for the RZ-1, and you will want to use a transducer with better-than-average sensitivity. The amp is not designed to fill an airplane hanger.

The back panel includes three types of digital inputs: coaxial, optical, and a USB input (24-bit/96kHz) to support the playback of high-resolution PC-based music files. (The S/PDIF inputs support up to 192kHz/24-bit data.) The DAC chip is the AK4392, produced by Asahi Kasei Microdevices Corporation. The input receiver, digital filters, and Delta-Sigma modulator are all capable of 32-bit processing. The digital filter upconverts all input data to 24-bit resolution. Esoteric’s extensive high-end design expertise was also applied to the USB input, which is outfitted with a USB isolator for the USB power supply and signal lines. The feature prevents external interference from polluting the audio signal. Esoteric literature states that two different types of user-selectable digital filters for PCM signal-processing are available—a finite impulse response (FIR) digital filter, and a “short-delay digital filter to remove the pre-echo effect inherent in impulse waveforms.”

Convenience and ergonomics are primary to the RZ-1 experience. There are a lot of functions. (A sleep timer? You bet.) So I was expecting a glitch or two. But even with the extent of the audio switching available, the unit operated without a problem. And this included the USB DAC, which was immediately recognized by my MacBook; I had music up and streaming immediately. The sonics were impressive, even low-bit-rate MP3 tracks became listenable, and lossless sounded very good, indeed.

I gained a special appreciation for the flexible nature of the RZ-1. I liked being able to plug in the optical from the satellite box or stream from iTunes out of my Mac. I also relished giving my SACD collection a much-needed workout since my old Sony DVP-9000ES was laid to rest. I’m of two minds regarding the RZ-1’s reliance on the remote control, which pares down the front panel to a just a handful of low-profile buttons. There’s no rotary volume control, just pair of up/down controls. I get it. But I also think that in light of the premium price, the remote control shouldn’t look like Esoteric’s off-the-shelf units either. Something a bit more flattering, and in league with the style of the RZ-1 itself. It’s also overly sensitive to other IR remote controls in the room—to the extent that I had to unplug the RZ-1 in order to reboot communications between the remote and the amp.

As I began this evaluation my antennae were up for any telltale signs of the sonic compromises common to many all-in-one components—dynamic constriction, a limited soundspace, lean tonal balance, crumbling low-level resolution paramount among them. What I heard, in fact, was a vivid and open personality, free from constriction. Overall spectral balance was on the lighter side but accompanied by transients and microdynamics that were quick and finely resolved. There was nothing etchy or flinty in the treble range, and midrange timbres were very natural. This trait is especially desirable during SACD playback, which lives to reproduce low-level cues and treble air. Part of this is likely due to the lack of electronic noise from the RZ-1—backgrounds are very quiet. It’s no mean feat to isolate this much analog and digital circuitry in such close confines.

Although its bass response won’t give you a heart attack and macrodynamics are less than Force Ten, the RZ-1 is surprisingly energetic and firmly in control of complex orchestral passages. The bass is not heavily loaded in mass and weight, at least not in the manner of big-block engines like a Plinius or the ARC DSi200. These amps can summon a level of galvanic force that seems to well up from the baseboards and set your legs resonating like tuning forks. The RZ-1 will touch hint at such power, but it finally lacks the muscle to summon up that kind of low-frequency energy. For example, Chris Cheek’s baritone sax during Jen Chapin’s “You Haven’t Done Nothin’” [ReVisions: Chesky] is simply not as explosive and bloomy at the bottom of its range. Likewise, Edgar Meyer’s bass doesn’t sustain the same thick resonant decay that a big amp can extract from the tracks on Appalachian Journey [Sony].

The Esoteric’s tonal balance was unwaveringly neutral with just a shade of darkening in the treble. I listened repeatedly to a pair of Jennifer Warnes’ tracks from The Hunter, “Way Down Deep” and “Lights of Lousiane,” and confirmed that in the tonal sense they didn’t differ significantly from my reference ARC. The talking drums were making their reverberant voices heard, the acoustic guitars were clean, quick off the string, and nicely sustained. And low-level detail was excellent. A favorite test track for this comes during James Taylor’s “Long Ago and Far Away” from Mud Slide Slim [Warner], where a young Joni Mitchell’s luminous harmony vocal and fading vibrato chase after Taylor’s lead oh so softly and pristinely. In fact the only tiny piece of the sonic puzzle that seemed to be missing was the lift and air on the top of her vocal, which seemed to drift into infinity out of the ARC but to roll off and decay a little more rapidly with the RZ-1.

In previous encounters with compact electronics, it’s often a three-dimensional soundstage that’s the first thing to suffer. It tends to contract in width, sometimes dramatically. I listened to a variety of SACD and compact discs including the Brahms Symphony No. 4 and in every case came away impressed with the width, depth, and imaging precision of this combi-amp. The RZ-1 does reduce the overall scale of images and the ambient environment containing them, but it won’t flatten space or shorten soundstage depth. Symphony orchestra reproduction is uncongested and individual sections are well layered. Its ability to resolve delicate interior instrumentation and low-level performance details was excellent for a component in this segment. SACD sources like the Brahms maintained the characteristic tight bass control, low-level dynamic ease, and upper-frequency effortlessness that defines the format.

Esoteric has carved a unique niche with the RZ-1. Cast as an ideal den component, it will certainly curry the favor of discriminating enthusiasts looking to complete a well-dressed Esoteric household. But I think Esoteric got it wrong when it promoted the RZ-1 as a component for casual listening. Fact is, you’re going to enjoy giving the RZ-1 your undivided attention.


Power output: 100Wpc into 6 ohms
Inputs: Analog, two RCA; three digital, coaxial, optical, USB
Dimensions: 15.75” x 3” x 14.5”
Weight: 20 lbs.
Price: $6000

7733 Telegraph Road
Montebello, CA 90640
(323) 727-7627

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