Rotel RB-1590 Amplifier and RC-1590 Preamp Review

Audio amplifiers have exactly one job to do—take an electrical signal and magnify it without adding distortion. That goal was elusive in the vacuum-tube era, as well as in the early days of solid-state amplification. However, modern amplifier designs have evolved to the point where measurable distortion is typically below audible thresholds on most properly designed solid-state amps.

With refined modern amps like Rotel’s 2-channel RB-1590, the specifications hint at true transparency. A flat frequency response often extends well into the infrasonic and ultrasonic realms, while most modern amps—including what you find in an AVR—exhibit vanishingly low levels of distortion. In fact, there’s vigorous debate about whether solid-state amps operating within specifications all sound the same.

Preamps are, by necessity, more complicated than amplifiers. At their most basic, preamps offer source switching, a volume control, and perhaps tone controls. Often, a dedicated phono preamp is part of the package, as is a headphone jack. Many modern preamps add additional features such as high-end DACs (digital-to-analog converters) and support for wireless connections, not to mention subwoofer outputs and advanced room correction. As manufacturers add more features, the device becomes a pre/pro (preamp/processor). The Rotel RC-1590 in this review is a true 2-channel preamp, eschewing DSP processing for a more “audiophile purist” approach to handling sound.

The RC-1590 takes an old-school audiophile approach to embracing new-school digital sources. It starts where all good preamps must start: with impeccably spec’d analog inputs and outputs. Notably, it is an audio-only device, with nary a video connection to be seen. The RC-1590’s architecture is a reflection of this audio-above-all approach—it’s basically a high-end DAC and an analog preamp that share the same chassis.

Audio enthusiasts spoiled by the feature sets of modern AVRs and pre/pros will lament the absence of any controls that depend on DSP, such as setting the distance and crossover point of a subwoofer or applying EQ or room correction. That’s simply not how the RC-1590 rolls; the preamp is analog. Digital sources pass through the DAC, while analog sources proceed directly to the outputs; aside from defeatable tone controls and a mono-summed signal for two subwoofers, the audio is left alone.

It took me a while to understand the charms of the RC-1590, but once I figured out what the system was about, I started to have a lot of fun with it. Mostly, this review is about my experience using the RB-1590 and RC-1590 to audition a wide selection of speakers. It is not a deeply technical review—I lack the facilities to confirm or deny most of the listed specifications. Rather, it is an experience report from a fan of AVRs, DSP, and all the other digital goodies that the Rotel system rejects for the sake of simplicity and analog purity.

Features

The RB-1590 ($3000) is a 2-channel class-AB amp with a rated output of 350 watts/channel into 8 ohms. It offers balanced XLR and unbalanced RCA inputs, dual speaker terminals for bi-wiring, and a 12-volt trigger input and output. The amp is housed in a very handsome aluminum chassis that is a perfect aesthetic match for the RC-1590 preamp. My review units came in silver, but they are also available in black.

The amp’s custom-made twin-toroidal transformer and dual-monoblock design uses high-quality British slit-foil capacitors. It boasts a frequency-response spec of 10 Hz – 100 kHz (+/-0.5 dB). The rated signal-to-noise ratio (A-weighted) is 120 dB, and THD is specified at less than 0.03% from 20 Hz to 20 kHz.

The damping factor is listed as 300 (1 kHz, 8 ohms), and channel separation is greater than 50 dB. The amp can drive 4-ohm loads, but Rotel does not list a power spec for that. Its 5U chassis is rack-mountable, and the amp weighs 84 pounds—we’re talking about a very substantial piece of hardware here.

The RC-1590 ($1750) is a preamp that’s intended to compliment the RB-1590. It offers an AKM premium DAC with an eye-popping resolution of 32-bit/768 kHz. The analog and digital sections of the RC-1590 each have their own toroidal transformer, and the preamp’s design keeps the two sections isolated from each other.

Performance specs for the RC-1590 put it in flagship audiophile-preamp territory—THD is under 0.002% from 20 Hz to 20 kHz. Frequency response fluctuates by only +/-0.1 dB from 10 Hz to 100 kHz when using the line-level analog inputs, +/-0.2 dB from 20 Hz to 20 kHz for the phono input, and +/-0.5 dB from 20 Hz to 20 kHz for the digital inputs. The S/N ratio (A-weighted) is 112 dB for the line-level analog inputs, 108 dB for the digital inputs, and 80 dB for the phono input.

You get a lot of input and output options with the RC-1590. When it comes to analog, it sports one pair of balanced XLR inputs and two pairs of balanced XLR outputs. It also offers phono, CD, tuner, and auxiliary unbalanced RCA inputs, two pairs of unbalanced RCA outputs, and one pair of unbalanced RCA line outs. Additionally, the preamp has two mono-summed subwoofer outputs.

On the digital side of things, the RC-1590 includes three optical inputs, three coaxial inputs, a rear USB input that includes DSD support and handles up to 24-bit/352.8 kHz PCM, and a front panel USB input for connecting an iPod/iPhone/iPad. It also includes a pair of digital outputs, one optical and one coaxial. For those who want to listen to audio from their smartphone or tablet, the RC-1590 also supports Bluetooth with aptX for CD-quality streaming. Notably, the RC-1590 preamp sports a 3.5mm headphone jack that operates concurrently with the line outputs—plugging in headphones does not automatically silence the speakers.

In addition to the preamp’s substantial remote, you can also control the unit over IP through a built-in Ethernet connection as well as an RS-232 serial connection—in other words, it integrates nicely with a home-automation system. Twin 12-volt triggers, an external IR-receiver input, and a pair of Rotel Link connections round out the preamp’s integration-friendly features.

Ergonomics

There’s not much to discuss about the ergonomics of the RB-1590 amplifier. It’s big, it’s heavy, and it has one button on the front panel—the power switch. The speaker terminals on the rear panel are very generous in size and will accommodate 10-gauge bare wire or banana plugs.

The RC-1590 preamp takes a decidedly old-school approach to its interface, but ergonomically it is very intuitive and easy to use. The two-line, dot-matrix monochrome display is minimalist, but it manages to convey all the information needed to operate the preamp. There’s a dedicated button for each input as well as discrete controls for tone adjustment and for operating the setup menu. Also, the RC-1590 features a fairly large rotary volume control that offers 100 steps of adjustment.

The rear panel of the RC-1590 is nicely laid out, with clear labeling and plenty of space between connections.

The remote is a bit of an anachronism. It’s huge, it’s made of plastic, and unless you buy a Rotel CD player and/or tuner, most of the buttons serve no purpose. I think a compact metal remote would have been a better compliment to a system such as this. On the other hand, there’s no way you’ll lose the provided remote, and it’s pretty solid.

The menu system of the RC-1590 is notably simple. You can adjust the bass and treble tone controls—or defeat them. In the setup menu, you can choose fixed or variable gain for each input and enable or disable USB audio class-2 playback, which allows the unit to accept 192 kHz sample rates from a PC. The setup menu is only one level deep, so you can’t get lost in it.


The front panel and remote control of the RC-1590.

Setup

As noted earlier, I had to adopt the mentality of a 2-channel audio aficionado before I was able to get the most out of the Rotel system. That meant coming to terms with the total absence of bass management, parametric EQ, and timing correction that I take for granted when working with AV gear. The advantage of avoiding DSP is a system that offers audiophile performance plus simplicity without breaking the bank.

I set up the system in my 2-channel listening area, which is an 11-foot-wide, 16-foot-deep space with an 8.5-foot ceiling. It’s part of the open-plan first floor of a Philly row house, so the room itself is actually 35 feet deep, and there’s no wall behind my head at the main listening position.

Most of the review consisted of playing music (and some test tones) on as many different speaker systems as I could get my hands on. I used an audiophile-approved speaker configuration throughout the process, with the speakers positioned five feet in front of the forward wall, and six feet apart from one another.

I disabled the tone controls for all my listening—in my opinion, they are too blunt a tool and usually unnecessary. More often than not, I simply listened to towers playing full range, with no subs. Room measurements of sine sweeps revealed a respectable in-room response at the main listening position, with some measurable room-related effects in the bass region, but no big bumps or notches.

Although I did a lot of listening to towers running full range without subwoofers, I also used subs a few times—some genres demand bass reproduction that dips into the infrasonic, and I had no true full-range speakers on hand. Since swapping subs is not really necessary, I went for the biggest subs I had available to me—a pair of Klipsch R-115SWs.

In order to better integrate the subwoofers, I used a miniDSP 2×4 processor between the RC-1590 and the subs. It applied response-flattening EQ and a custom lowpass filter to the RC-1590’s raw subwoofer output, allowing me to tailor the subs’ response to each speaker system I used them with.

I positioned the subs against the side walls and slightly ahead of the speakers in order to achieve a natural time alignment. With this system, you can’t add delay to the main speakers—for proper time alignment, the subs can’t be farther away from the listener than the speakers.

Ultimately, I used the system to play tunes and tones through eight different pairs of tower speakers and five different pairs of bookshelf speakers from eight different brands. The speaker positioning remained roughly the same for all of the speakers, with minor tweaks to the toe-in depending on the particular model.

My primary source of music was a Sony VAIO laptop that I have dedicated to music playback. It runs Tidal, iTunes, Google Play, Spotify Premium, and Foobar 2000 (for hi-res playback). An SSD drive also holds my ripped CD collection, which I usually play through iTunes. The laptop was connected to the RC-1590 via USB.

The system also featured a Chromecast Audio as a source using the optical-digital output of Google’s clever little player. All I can say about the Chromecast is it’s truly remarkable what $35 buys these days.

Finally, I did play some vinyl records through the system using a vintage Dual turntable equipped with a Stanton 681 EEE cartridge. I’m not a huge vinyl-record fan, but I can report that the phono input on the RC-1590 works.

Performance

Whether we’re discussing amps or automobiles, there’s something supremely satisfying about knowing you have more power on tap than you need, and that satisfaction grows when you can tell that power is backed by refinement. The combination of the RB-1590 amp and RC-1590 preamp provided exactly such an experience.

When I used the most sensitive speakers I have on hand—Klipsch’s RP-280FA (98 dB/W/m)—I never heard any hiss unless it was a part of the recording. The backdrop of dead silence remained regardless of how much I cranked the volume. Furthermore, when I used the least sensitive speakers at my disposal—the Pioneer Elite SP-EFS73 (86 dB/W/m)—there was plenty of power available to make ’em sing. In other words, it hardly matters what kind of speakers you use with the RB-1590; it’s got both the juice and the finesse to make the most of them.

As part of the review process, I used a Focusrite Scarlett 2×2 digital audio interface and REW (Room EQ Wizard) software to take frequency response measurements. I measured sine wave sweeps generated by REW directly from the RC-1590’s analog outputs, and I used a Can Opener (really just a couple of resistors in a box) connected to the RB-1590’s speaker terminals to measure the amplifier’s frequency response.

The RB-1590’s flat response, inaudible distortion, low noise floor, and high power output repeatedly brought out the best qualities in all the speakers I hooked up to it. I measured frequency response of the amp from 4 Hz to 24 kHz, and found it met the published specs—bass response was down only 0.4 dB at 10 Hz, and it was flat from 20 Hz right on up to my 24 kHz measurement cutoff.


The RB-1590 stayed within its published frequency response specs when measured from 4 Hz to 24 kHz.

Simply put, the amp never, ever stumbled—on any piece of content—with any of the speakers I connected to it. Granted, I don’t have six-figure super-speakers to test the amp with, but that’s a whole different ball game.

At this point, it’s worth acknowledging that you can spend less for an amp with similar wattage and specifications—hello Emotiva—but in the grand scheme of things, the RB-1590 offers reasonably priced, high-quality amplification in an attractive and reliable package. I’m sure the forum comments will include some discussion on this particular point. To my taste, the Rotel RB-1590 looks, sounds, and feels like it’s worth the asking price.

Similarly, I’m hard pressed to find much to criticize in the RC-1590’s performance, aside from a lack of bass management. The audio it produced was crystal clear and free of any audible coloration. When I measured frequency response, the result was ruler flat from 4 Hz up to my measurement limit of 24 kHz—and that’s with a digital input, which easily surpasses Rotel’s spec for a digital input (20 Hz to 20 kHz +/-0.5 dB).


The RC-1590 exhibited ruler-flat frequency response from 4 Hz to 24 kHz when using the USB input, easily exceeding its published spec.

In the months I used the system, it did not falter once. Even when torture-testing the gear by running 3-Hz sine waves through it with the volume cranked, the end result was woofers moving in and out in an eerily slow manner. While I’m not in a position to definitively declare that all modern DACs and amps are effectively transparent, I can say that—to my ears—the Rotel system featured in this review was indeed transparent.

Listening

KEF’s R500 towers rendered some amazingly detailed, wide, and deep soundstages—it all depended on the mix. With a rated sensitivity of 88 dB/W/m, they require some juice to really get going. I especially enjoyed listening to the entire Bassnectar catalog through the Rotel/KEF combo. Adding the two Klipsch subs with a low-pass filter set to 50 Hz yielded ridiculously impactful yet well-integrated bass that took the dubstep listening experience to a higher level. With most music genres, letting the R500s run on their own (no subs) offered plenty of tight bass as well as clean, clear, dynamic sound that satisfied everyone who heard it.

When I used the system to power Klipsch’s RP-280FA towers, I experienced an embarrassment of dynamic riches. The RB-1590 amp just cruised right along, serving up a watt here and there until called upon to deliver a crescendo of some type. There’s no logical reason I would ever max out this system in my home. The huge amount of headroom offered by the Rotel/Klipsch combo—combined with the RP-280FAs’ ability to reproduce bass as low as 30 Hz—lent a live-concert feel to jazz and classical recordings. However, my favorite use for the badass Klipsch towers was blasting rap music.

Adding the subs to handle bass frequencies 30 Hz and under brought out the awesome in a many of my favorite tracks, including a wide variety from artists like Lil’ Wayne, Danny Brown, Alchemist/Mobb Deep, Notorious B.I.G., B.A.R.S. Murre, Jay-Z, Nas, Wu-Tang Clan, and others. It was easy to get scary-loud with that combo, and yet the refinement and precision of the Rotel gear shone through.

Pairing the Rotel system with Paradigm’s Prestige 75F towers resulted in sound that was notably silky and smooth. Indeed, the combination was so sublime, I could listen to that system forever without growing tired of the sound. I particularly enjoyed revisiting some of my favorite albums of decades past, including some classic Thievery Corporation, Bill Laswell, and Orb albums. Who am I kidding—the Paradigms sounded great no matter what I played. Driven to their limits by the system, they exhibited perfect poise right up to the edge of what those speakers offer output-wise.

The RB-1590 was assuredly overkill for use with bookshelf speakers, and yet it was quite a treat to hear ELAC’s Debut B6 bookshelf speakers powered by the Rotel system. Those speakers have a lot going for them—the overall sound was smooth and relaxed, and imaging is notably good for speakers at their price point of $280/pair. Unsurprisingly, adding the subs to the ELACs yielded a deeper, more impactful listening experience—I could both hear and feel even the subtlest of deep sounds.

I’m quite fond of the GoldenEar Triton Five towers, the larger and more capable of the two models of passive floorstanding speakers the company sells (the other being the Triton Seven). GoldenEar specializes in holographic imaging, and that’s exactly what I got when I paired the Tritons with the Rotel rig. Frankly, a lot of systems I’ve heard at high-end audio shows don’t come close to the fidelity I experienced from this combination—even at five or ten times the price. Yes, I know that’s a cliché comment, but it’s true.

My experiences with the other speakers I tried with the system largely mirrored what I’ve described above. It did not matter if I was playing the Rotel rig through the SVS Prime Towers, PSB Imagine X2Ts, or Pioneer Elite SP-EFS73 towers; the speakers translated the uncolored output of the system into eminently listenable music—or unlistenable, in the case of a bad recording. This is not a stereo that veils sound, it’s true to the source; if you use it with speakers that are also neutral and true to the source, you’ll have a true hi-fi experience, guaranteed.

Conclusion

There are a lot of options out there when it comes to hi-fi stereo amplifiers and preamps. Rotel’s flagship offerings are interesting because they offer an attractive balance between price, aesthetics, and capability. Yes, you can spend less and get similar specs from a few other brands. You can also spend a lot more and wind up doing worse, performance-wise. Rotel exhibits a particular aesthetic and design philosophy; once you experience the gear, you’ll know if you dig it.

When it comes to the RB-1590, I’m skeptical that it’s possible to make an amp that sounds significantly more transparent than it already is. In the grand scheme of things, it’s neither the cheapest nor the most expensive option out there for a 350 W/channel stereo amp, but the impression it gives is that you are getting a lot of value for your money.

The RC-1590 may not be my cup of tea feature-wise (I happen to prefer coffee), but excellent fidelity combined with ease of use is the upshot of its audio-centric design. The preamp features truly ruler-flat frequency response and microscopic levels of distortion, meaning that it just gets out of the way of the music. The simple operation and stereo-purist feature set are not necessarily going to thrill DSP addicts used to the digital bells and whistles of AVRs and pre/pros, but 2-channel audio aficionados should find much to like in the way the RC-1590 goes about its business.

Ultimately, the Rotel RB-1590 amp and RC-1590 preamp combination creates a killer 2-channel rig that gives you the power and the precision needed to get the most out of a great pair of speakers, so you can enjoy the music. Of that, I am certain.

EQUIPMENT LIST

Sources

Sony VAIO Laptop running Tidal, iTunes, Spotify, and Foobar 2000
Google Chromecast Audio
Dual Turntable with Stanton 681 EEE cartridge

Speakers

GoldenEar Triton Five
GoldenEar Triton Seven
KEF R500
KEF R100
Klipsch RP-280FA
Klipsch RP-160M
Paradigm Prestige 75F
Pioneer SP-EFS73
Pioneer SP-EBS73
PSB Imagine X2T
PSB Imagine XB
SVS Prime Tower
ELAC Debut B6

Subwoofers & DSP

Klipsch R-115SW
miniDSP 2×4

Cables

Hosa HMIC003 Pro balanced XLR interconnects
KabelDirekt 3-foot RCA interconnects
Mediabridge Ultra RCA subwoofer interconnects (25-foot)
Monoprice 12-gauge OFC speaker cable
Monoprice 3-foot Toslink to mini Toslink cable
Monoprice 3-foot USB 2.0 cable