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.