Review: Audio Research I/50 Integrated Amplifier

Tung-Sol introduced the world to the 6550 beam tetrode vacuum tube in 1954, with early production coming out of their Bloomfield, NJ plant. I grew up about 8 miles away and that plant, the Electron Tube Division, remained in operation until I was a teen. So a long time ago but not a looong time ago.

J. Gordon Holt said of the Audio Research Dual 150 power amplifier, that employed 6550s, in his Stereophile review from 1976: “What does this betubed monster sound like? Nothing. Simply nothing at all.”

At the 1992 Consumer Electronics Show, AR founder William Z. Johnson showcased a new line of Reference products, which never made it into production, but birthed the 6550-endowed VT-150 about which Robert Harley concluded in his Stereophile review from 1994: “The VT-150 is as far removed from ‘hi-fi’ as I can imagine, and closer to the live musical experience than I’ve heard from any amplifier.”

I offer these anecdotes as bits of (important) history, something Audio Research, which was founded in 1970, has and has made.

The new(ish) Audio Research I/50 Integrated Amplifier on review offers 50Watts of output power from 2 pair of JJ 6550 vacuum tubes, clearly a familiar foundation for the company. Joining the two matched pairs of 6550s are three 6922s (1x input, 2x driver) and for a fun visual treat a pair of AR’s LexieTubes sit in front and light up green with a start up count down and, once warm, display the volume level and active input. A 1/4″ headphone jack also sits on the high gloss black top panel along with the power button, volume and input select knobs. A wafer thin metal remote is included.

The I/50 is built at Audio Research’s Minnesota HQ and the aluminum top plate surround has a Cerakote ceramic finish that is offered in 6 colors: Gold, Natural (Silver), Red, White, Black, and Blue. Color choice is a good thing in my book and the Cerakote process enhances a number of physical performance properties including abrasion/wear resistance, corrosion resistance, chemical resistance, impact strength, and hardness. according to KECO Engineered Coatings, Inc. This ain’t just paint.

The review unit came with the optional Phono module that provides 42 dB of gain making it compatible with moving magnet and high-output moving coil cartridges, as well as the optional DAC module that offers USB (supports PCM resolutions up to 384kHz and DS128), Toslink, and Coax inputs plus Bluetooth for convenience. There’s a total of three line level inputs (2x RCA, 1x XLR) and speaker binding posts with 4 and 8 Ohm taps.

I paired the I/50 with a number of dance partners including the review Wharfedale Dovedale (more info), the review Volti Rival SE (more info), and the Barn resident DeVore Fidelity O/96 (review). Speaker cables included the AudioQuest ThunderBird Zero (A-Side) and Robin Hood Speaker Cables (B-Side), and I used the review Technics SL-1210GR (more info) mounted with the Ortofon 2M Black cartridge on the B-Side as well as the Barn resident Michell Gyro SE/T8 tonearm with the same Ortofon cartridge on the A-Side to put the I/50’s optional phono stage through its paces. The optional and included DAC received its bits from the Barn resident Auralic AIRES G1.1 (review) on the B-Side and the review Auralic ARIES G2.2 (more info) on the A-Side. A length of AQ Diamond USB cable made the physical connections. For the majority of review time, I let the I/50’s internal DAC do the converting so unless otherwise noted, that’s what I’m talking about in the following listening notes.

Here’s a reviewing secret—writing about gear that has very little sound character is not easy and I struggled, as much as one can when writing about hifi, finding my hook into describing the sound of the Audio Research I/50 because it has very little character of its own. All that being said, even very little sonic character imparts is own flavor on the accompanying speaker and the trick when system building is finding good mates. Just like in real life with relationships.

The I/50 sounds, regardless of the speaker pairing, powerful, robust, grain free, cool, clear, precise, and always in complete control from the lowest lows to the highest twinkles. It coaxed some very fine bass performance from every speaker pairing, the kind of bass performance that allows for the appreciation of the player’s skill and his instruments sonic qualities which is what we want as opposed to indistinct sonic softballs lobbed into the listening room. These qualities combined to allow for listening through the hifi and into the music in play, something I assume we all want, more or less, from our gear in the service of tunes.

I’ve been following, as a fan not a stalker, Nika Roza Danilova as Zola Jesus since 2010’s The Spoils and have had the pleasure of seeing her live in NYC’s very much missed Other Music and the tiny nearby Cake Shop on Ludlow Street in 2010. Both venues were intimate affairs so in both cases I was but a few feet from Nika Roza Danilova’s big voice. Alive in Cappadocia from 2022 features just Danilova accompanying herself on piano recorded live in a 2,000 year old chapel. Just (big) voice, piano, and church (reverb). Playing through the I/50 as DAC and amp into the DeVore O/96 on the Barn’s A-Side, this music transformed the Barn’s dimensions and mood into a cavernous, ancient space where every note, cluster, and soaring vocal demo’d the Barn’s walls and ceiling leaving quivering ephemeral beauty in its place. Lovely.

When I want relaxed beauty, one easy go-to is anything featuring Adrienne Lenker. 2014’s a-sides with Buck Meek is one great example for its simple exquisite-ness expressed via guitars and harmonies. Once again paired with the O/96, the ripeness of the sound of this record came through loud and clear enough to effortlessly pass through the turnstile of reproduction into pure music enjoyment. I will share that the Barn resident and pricier, by about $3k without a phono stage or DAC, Leben CS600 endows music with a fleshier feel while offering similar drive and control. To say it another way, I find the Leben makes music sound richer, more ripe, which grants me easier emotional access. That said, the I/50 gets me a good way there for considerably less scratch.

Of the three speaker partners, my favorite combination found the I/50 lighting up the Wharfedale Dovedale. While I’ll dig deeper into the Dovedale’s sound in that review, I will say they lean toward a browner kinda sound, woody if you will, imbuing music with an almost sepia tone so the I/50’s clear cool control offered a very nicely balanced sonic partner, according to my taste. My least favorite, there had to be one if there was a most favorite, was the Volti Rival SE, which to my ears want a bit more meat, a bit more tonal saturation to fill out their very resolving and lively sound. Again, we’ll talk in greater detail about the lovely Rival SE’s in their review because there’s loads more to add to their plus column.

Nocturnes from the Boxhead Ensemble is a soundtrack for a film that never came to be featuring Michael Krassner on guitar/organ/FX, Fred Lonberg-Holm on cello/harmonica, Frank Rosaly drums, and Jacob Kolar playing prepared piano. This is delicate, almost skeletal music with silences that would make John Cage blush and sad slide guitar that would make Ry Cooder weep (hello Paris, Texas). Nocturnes is also a lovely sounding record and with the I/50 driving the Dovedale’s, the Barn’s B-Side came alive with the stark beauty to be found in these instrumental voices. The I/50s optional DAC will run you $1k and you’d be hard-pressed to better it for that kind of money.

It is worth noting that it’s just a DAC, so you’ll need to feed its USB, Toslink, or Coax input with your own device of choice. One neat alternative that plays very nicely in this price ballpark is the recently reviewed Wattson Emerson ANALOG streaming DAC that offers a slightly more resolving sound, plus streaming, for $1750. This apparent greater resolution translates into more realistic and incisive sparkle glinting off acoustic guitar strings, a harmonica with a more ‘reedy’ sound (less metallic), and a clearer sound image. But just like the differences with the Leben, the I/50’s DAC got me a good way there so if you like simple, the optional internal DAC is your best friend.

Of course, me being me, I also tried a few more expensive DACs with the I/50 like the Barn resident totaldac d1-unity (review) and, surprise surprise, it sounded even better. One thing that’s worth noting while we’re here—the review sample Ideon EOS DAC (review) did not get along with the I/50—as soon as I hit “Play”, the sound of loud pops and static found me running for the Mute and Power Off controls. While the EOS’ specs, which were recently revised on the Ideon website, state the RCA output at 2.2V RMS, my one guess is the review sample’s was higher. And I guess this because I did not have any issue with the totaldac (listed as 3.5V on their website), Wattson Emerson (2.0V RMS), or review sample Merason DAC1 Mk II (1.5V RMS) (more info) when paired with the I/50. To fill out this picture, I also did not encounter any issues when pairing the Ideon EOS with other integrated amps including the Soulution 330 (review), Thöress EHT (more info), or the Leben CS600.

I’ve yet to meet a phono stage I don’t like and the I/50’s optional phono module is very easy to like, if not love. At $750, I suggest a get it and forget it approach as you’ll probably spend too much time and too much money trying to beat it for the same spend. It certainly loved the Ortofon 2M Black as much as I do, and together they made my records come alive with grace, fluidity, and enough detail to make me smile and dance. For illustrative purposes, let’s talk about ANOHNI and the Johnsons stunning My Back Was A Bridge For You To Cross LP, released on Secretly Canadian earlier this year. If you don’t know ANOHNI and the Johnsons, formerly known as Antony and the Johnsons, and you like beauty you’ll want to get acquainted.

From “It Must Change”:

“You know how they always said that light was the opposite of darkness? / It’s just fire in darkness, creating life / So those opposites, they don’t exist / It’s just an idea that someone told you”

As a system, with the I/50 playing this record from either the Michell or Technics ‘tables and through the Wharfedales, I got the full message, the complete spectrum of emotion packed into this lovely album with as much flesh, blood, and sorrow as I could take. Once again, if you like simple the optional internal phono stage is your best friend.

Stepping outside of sound, living with, looking at, and using the Audio Research I/50 was pure pleasure. Before it arrived, based on looking at photos, I didn’t think I’d care for the “Gold” finish but I was wrong. It grew on me faster than a cartoon lump and the Gold matte Cerakote contrasted with the reflective high gloss black top panel creating an endless symphony for the eyes. And while the included and handsome remote is handy, I preferred touching (and turning and pressing) those dials.

And yea, it does this in the dark.

While the placement of the headphone jack on the top plate only inches from those tubes made me a bit nervous—what if I got the uncontrollable desire to dance around like a madman and accidentally dragged the headphone cable too close to the heat of those 8550s?—the sound the I/50’s headphone amp made when mated to the ever-lovely Meze Audio 109 Pro ‘phones put those fears to rest by placing me inside the music.

According to my ears, Niecy Blues’ debut album Exit Simulation is a perfect record for personal listening, the kind of subtle, slow, smoky blues-gospel-tinged haunting music that comes to greater life through a nice pair of headphones paired with an amp that can drive ‘em. And the I/50 drove the Meze 109 Pro’s to delightfully soul-stirring heights, bringing every nook, cranny, crackle, and spirit within Exit Simulation to life inside my head. This record is the kind of record that grows over time, becoming more complex and more lovable the more you listen, at least that’s how it’s worked on me, and the I/50/109 Pro combo introduced me to new depths of meaning, new subtle sonic recesses previously out of range allowing for even greater connection to this stunner of a record. Yes, another best friend awaits inside the I/50’s lovely form and function.

Truth be told, I was ready to love the Audio Research I/50. And I found that love when paired with the Wharfedale Dovedale and Meze 109 Pro headphones most of all. If your Want List includes faultless build quality, eye-popping looks (that comes in 6 different colors), and a clean, clear and controlled window onto your beloved music, the I/50 may very well be your new best friend.

Audio Research I/50 Integrated Amplifier
Price: $5500, Phono Module +$750, DAC module +$1000
Company Website: Audio Research


Power Output: 50 watts continuous from 20Hz to 20kHz. 1kHz total harmonic distortion typically 1% per channel, below 0.1% at 1 watt (Note that actual power output is dependent upon both line voltage and “condition” i.e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not critical)

Power Bandwidth: (-3dB points) 10Hz to 22kHz
Frequency Response: (-3dB points at 1 watt) 7Hz to 30kHz
Input Sensitivity: 1.25V RMS for rated output.
Input Impedance: 100K ohms Balanced, 48K ohms Single Ended
Output Polarity: Non-inverting. Balanced input pin 2+ (IEC-268)
Output Taps: 8 ohms, 4 ohms
Power Requirements: 105-130VAC 60Hz (210-250VAC 50Hz) 252 watts at rated output.
Tubes Required: 2 matched pair 6550WE; 3-6922 (1 input, 2 driver).

Width 16.5” (42 cm)
Height 7.25” (18 cm)
Depth 13.5” (34 cm)

Weight: 40 lbs (18.1 kg); 51 lbs (23.1kg) shipping weight.