Review: Unison Research Simply 845 Integrated Amplifier

I don’t know anyone who looks at glowing vacuum tubes and thinks—Damn! That’s ugly! My best guest is light, and heat, still touch most humans in places that are connected to survival.

Our interest in the beautiful glow produced by the Unison Research Simply 845 Integrated Amplifier, not to mention the significant amount of heat it generates, goes beyond appearance because this light show is but a byproduct of its main job of amplifying a music signal. What’s more, we really want to know about the quality of that amplification as it relates to reproducing music.

While there’s no doubt the Simply 845 makes the signal it receives from source gear louder, we need to know if it does so without mucking things up, without adding or subtracting stuff that makes music sound less believable, less like we know how it’s supposed to sound. And the best way I know of to test this process is to listen to music, lots of music through, ideally, a few different accompanying loudspeakers, and see how it makes us feel. From our heads to our toes and especially everything in between.

So this is exactly what I’ve been up to in the time since the Unison Research Simply 845 Integrated Amplifier arrived in Barn at the beginning of May over a month ago. In that time, the Simply 845 spent some time driving the Dynaudio Contour 60i (review), Perlisten S5t (review), and the DeVore Fidelity O/96 (review) and its sound, or better stated as the way it made music sound was nothing short of glorious.

Yes, glorious is the right word for the rainbow explosion of music energy released in Barn by the Simply 845 driving, most notably, the Barn resident DeVore O/96. A very full palette of tone color coupled with control, drive, and space—gobs of spacey space—filled this place with the kind of music reproduction that reached deep inside moving past sound directly to effect.

The Unison Research Simply 845 is, from a bird’s eye view, a pure Class A single-ended directly-heated 845 triode-based integrated amplifier (a SET) that puts out 23 Watts per channel. This specimen under review is the first to make its way into the world from the Italian company and it sits just below their Absolute 845 flagship model which was first released in 1994 (!). Unison was founded in 1987 (!) and the SIMPLY TWO was their first integrated amp, an EL84-based Class A/B design. The Simply 845 uses handmade in-house custom transformers, ECC82/12AU7s in the preamp stage and a Japanese-made ALPS RK27 motorized volume control. Those triodes, which are branded Unison Research, are self-biasing so we’re talking about plug in (the tubes and cables) and play.

From the company:

The Simply 845 uses very thin Mylar and Polypropylene insulators suitable to contain parasitic capacitance and dispersion of magnetic fluxes as much as possible thus achieving an extended frequency range and very low harmonic distortion.

In addition, the ferromagnetic core employed is considerably different from cores commonly used in audio products and consists of a stack of thin laminations of a special alloy of iron and silicon all insulated from each other, the molecules of which are oriented and fixed in a stable manner to facilitate the flow of the lines of force of magnetic fields.

Four RCA line level inputs, a Sub and Tape Out join a pair of speaker binding posts and IEC inlet make up the rear panel’s story.

The Simply 845 sports thick curvaceous wood accents in Walnut or Cherry, the review unit wears the former, with a silver, bronze, and black metal & steel body that weighs a lift-with-your-legs 67 lbs. Woof! The power switch sits on the front right side and once flipped it takes but a few seconds for music to flow. The included tube cage spent most of its Barn time on the sidelines as I know better than to touch a heated vacuum tube, especially an 845, and I’m the only person in the Barn. I half expected to see some Barn mice curled up near their heat but apparently they know better, too. If you have children or curious pets, I’d put that tube cage to use.

There’s nothing fat or flabby about the Simply 845’s way with music reproduction so you can put that tube amp myth to bed for the duration of this review. I have a sneaking suspicion that many a tall tale about tube amps sounding overly loose and woolly has more to do with poor system building, specifically asking low power tube amps to drive speakers that really need more power, than it has to do with how tube amps sound in general. For example, if you ever come across a review of a 10 Watt tube amp that’s used to drive multi-driver speakers with an 87dB sensitivity and an impedance that dips down to 4 Ohms or so, you know you can disregard whatever that reviewer has to say about how things sound. Think of it like gauging the performance of Ferrari Testarossa by taking it for a spin in the Gobi desert and concluding the engine is underpowered.

On this very note, I gave the Simply 845 a quick test ride with the recently reviewed Dynaudio Contour 60i—sensitivity 88dB (@ 2.83V/1m) and a 4 Ohm nominal impedance—and while there were some aspects of the sound that sounded glorious, bass was shy and ill defined and the overall presentation lacked control and definition. . .as expected. I found the Dynaudio’s loved power, the more the merrier, and the Simply 845 loved less demanding speakers. Like the DeVore O/96. I know you probably knew all of this already but I’m continually amazed to find so many people, including some ‘reviewers’, who don’t.

I also gave the Simply 845 time with the recently reviewed Perlisten S5t that offer a incrementally friendlier load on paper with a stated 89.5dB (@2.83v /1m) sensitivity and 4 Ohm nominal load that dips to 3 Ohms. And I was surprised by how well they danced—in some ways namely tone and texture but overall the sound sounded stuck to the speakers, as if music had a difficult time getting free. I ran through a few torture tracks including Marc Ribot’s “Midost” from his first Ceramic Dog LP and when things got gnarly and dense, this music sounded a bit confused, a bit too mushy lacking clear definition between the various elements. Perlisten recommends a minimum of 100 Watts of power drive to the S5t and that seems like a sensible recommendation. But let me point to the obvious and note that if the Perlisten were the only speakers I used in this review, you and I would have no idea what the Simply 845 is capable of. Review reader beware!

So I spent the majority of my Simply 845 listening time with the DeVore’s. Sources were the Auralic ARIES G1.1 Streamer (review) feeding the Mola Mola Tambaqui DAC (review) or the totaldac d1-unity (review) and the Michell Gyro SE ‘table/Michell T8 tonearm/Ortofon 2M Black cartridge, and Manley Labs Chinook Special Edition MkII Phono Preamplifier (review). All cables are from AudioQuest including ThunderBird interconnects, Robin Hood Speaker Cables, Diamond AES/EBU cable, and Thunder High-Current AC power cables plugged into a AQ Niagara 3000 power conditioner. The Box Furniture “Fallen A” held all components in chunky vibration free style.

Have you ever been listening to music and thought, “Damn! That’s beautiful.” And that thought was about the music, aspects of composition and performance, and sound? That’s exactly what I thought when Indigo Sparke—hey I didn’t pick her name but its 60’s vibe is like, right on—singing the title track from her 2022 album Hysteria. As the song unfolds, acoustic guitar accompanies her voice as it effortlessly slides up to her highest registers all silky smooth and inviting. With this system in play, this lovely simple music hung in the air with real human warmth blurring the lines between you are there and she is here, turning the listening experience into an event worthy of complete attention.

Speaking of beauty, Lucinda Chua’s YIAN from earlier this year oozes intimacy. For an amp that looks the part of dragon slayer, the Simply 845’s output transformers being larger and heavier than some amps, its way with delicacy is kinda surprising. I wish I had the Line Magnetic Audio LM-845iA Integrated Amp (review) here at the same time because in many ways it would make for the most interesting comparison. But it’s been nearly two full years since its Barn stay so any direct 845-to-845 comparison is not possible. That said, I have a sneaking suspicion, based on what I wrote and remember about the Line Magnetic amp, that the Simply 845 does delicate better. YIAN mixes many elements including electronics, bass, and strings and through the O/96 with the Simply 845 doing the driving each of these elements sounded fully formed, ripe with full harmonic voice.

Nabihah Iqbal’s DREAMER from April glistens with music’s healing powers, shimmering with hope and light. I’m reminded, at times, of the Cocteau Twins in their most ethereal moments with guitar and synths acting like waves turning into wings lapping along in time with Iqbal’s hushed vocals floating above all the way to the clouds. The Simply 845 delivered the finer, nuanced moments along with the solid foundation supporting the sky high float.

LP.8.2 from Kelly Lee Owens is a four track EP that contains some deep electronic bass mixed with layers (and layers) of sounds and vocals creating a veritable cathedral of sound in size. The Simply 845 did this music proud as loud as I cared to go reproducing that big throbbing bass on “Moebius” in all its rubbery goodness. Her voice and its echoes lived on another plane, reaching way up high in the Barn with echoed remnants trailing off for miles. Big music, big drama as loud as I would ever care to go make listening feel a bit dangerous which is exactly how things should feel.

Hilary Woods EP Feral Hymns makes an interesting bookend to LP.8.2 seeing as its elements—string orchestration, electronics, field recordings and vocals—are similar but the resultant music isn’t. The bowed bass on the opening track is positively menacing, a snarling growl of a sound, and this system delivered a dimensional quivering copy in Barn.

From the Woods:

“A collection of hymns set at dusk. Speckled memory, dust, earth, grit, ritual and chant – purged in the shadows. Unspoken bonds, primal pain, cyclical patterns, unsent love letters. Homemade recordings, made at home.”

Once again the Simply 845 proved capable of reproducing the delicate and the dangerous in equal measure where called for, the emotive one-two punch that turns music into moving experience. Bravo!

All that moving music energy and glowing good looks to boot. Anyone considering making a Unison Research Simply 845 Integrated Amplifier their own will, necessarily, take everything into account. This means that the design choices, both inside and out, will speak to certain people and I bet that some, based on looks alone and those glowing 845s, will be drawn to it like a moth to a flame. When partnered with sensible speakers, the Simply 845 is capable of drama, delicacy, and danger which transcends reproduction turning the act of listening into full-fledged experience.

Unison Research Simply 845 Integrated Amplifier
Price: $9995
Company Website: Unison Research
US Distributor Website: Fidelity Imports

Technical Specifications

Type: Integrated Valve Amplifier
Valves: 2 x 845 Selected 2 x ECC 82 / 12AU7 selected
Class: Classe A Output stage topology: Single-ended
Maximum Power: 23W
Bandwidth: 20Hz-50kHz, +0dB -1dB @ 12W
Feedback Level: 14 dB
Output impedance: 6 Ohm
Input impedance: 47 Kohm / 100 pF
Input: 4 line level Inputs: 1 Tape, 1 Subwoofer
Power Consumption: 300VA
Sizes: 37 cm x 26 cm x 57 cm ( L x H x D ) 14 1/2 x 10 1/4 x 22 1/2 inch
Weight: 30,5 kg – 67 lbs
Main Fuses: 5x20mm – 6.3 AT 100V-120V