Audio Research Corporation 40th Anniversary Reference Preamp Reviewed

Published On: November 28, 2011
Last Updated on: October 31, 2020
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Audio Research Corporation 40th Anniversary Reference Preamp Reviewed

Audio Research is a company with a long and respected history in the audiophile world. To honor that history the company created the 40th Anniversary Reference Preamp. Does the amp do Audio Research's legacy justice? Ken Taraszka investigates.

Audio Research Corporation 40th Anniversary Reference Preamp Reviewed

  • Ken Taraszka M.D. is an anesthesiologist by trade based in Tampa Bay, Florida. Ken is also a professional audiophile and home theater writer specializing in AV preamps and all facets of the audiophile market. In the past, Ken has been a staff writer and editor at He has also at times been a frequent contributor at


Audio Research Corporation began in 1970 with the goal of producing vacuum-tube preamplifiers and amplifiers, and have long been regarded as the makers of some of the finest high-end tube electronics in the world. The company's original products are still 100 percent supported by the factory and command significant resale values - as well as a near cult-like following. Fast-forward forty years to Audio Research's 40th Anniversary and ask yourself: what would you do to commemorate the occasion? Well, if you're Audio Research, you build something worthy of being called an Anniversary Edition, and given their outstanding reputation for building world-class preamplifiers, it was logical that this anniversary edition would be one. The Audio Research 40th Anniversary Edition Reference preamplifier is this commemorative piece. Retailing for a cool $25,000 and only in production for one calendar year, the Audio Research's 40th is a piece of audio jewelry few will ever own but all will likely lust after for years to come.

Additional Resources
• Read more stereo preamp reviews by's staff.
• Find a pair of Floorstanding Speakers or Bookshelf Speakers to pair with the preamp.
• Look for sources in our Source Component Review section.

The Anniversary Edition preamplifier is built beyond anything ever produced by Audio Research. Featuring a dual chassis design with one for the power supplies and one for the audio section, the two units are connected by two large umbilical cords and the power supply is connected with a 20 Amp IEC plug. The preamplifier has twice the power supply of any previous ARC preamplifier, and frankly more than many large amplifiers. The power supplies are completely separate for each channel, featuring separate low and high voltage transformers as well as vacuum-tube regulation (6550C, 6H30). The massive power supplies and power reserves ensure near limitless headroom and dynamics.

The Anniversary Edition's analog section is also isolated to maximize audio quality; featuring an all-tube, pure Class-A triode circuit that possesses zero feedback. A first for any tube preamplifier, the Anniversary Edition's audio gain circuit is a dual-mono design featuring eight 6H30 triode tubes, four for each channel. Further proof that the Anniversary Edition is unlike any preamp you've seen or heard, especially when it comes to ARC's attention to detail and performance, is its use of custom Teflon coupling capacitors each tipping the scales at more than two pounds.

The 40th Anniversary Reference preamplifier offers six stereo inputs and a dedicated home theater bypass for integration into 'hybrid' or dual use systems with two outputs and a tape out as well. All inputs and outputs are either single-ended or balanced. The analog unit is almost identical to their Reference 5 preamp except the buttons across the bottom of the faceplate are now surface mounted rather than recessed. A large central green OLED display that can be turned off for peak performance conveys all the information one could need, while the two dials on the left and right control volume and input. The buttons across the bottom cover mute, power, phase, processor or home theater bypass mode, Balanced or single-ended and mono.

Both the power and analog sections measure 19 inches wide, seven inches tall and 15.5 deep. The audio chassis weighs 29 pounds whereas the power supply chassis is 39 pounds, bringing the total system weight to 68 pounds. It's a serious piece, especially considering it's a two-channel preamp.

Audio_Research_40th_Anniversary_Reference_Preamplifier_Review_back.jpgThe Hookup
The 40th Anniversary Reference Preamplifier comes packed like the jewel it is. Both chassis come double boxed, with the inner box surrounded by a layer of dense foam. Inside, each piece is wrapped and padded for added security. All the necessary hardware is, of course, included. The tubes are wrapped and packaged in dense foam, and are numbered to perfectly mate to your specific preamplifier and additional tubes are provided as spares. The modest plastic remote, power cord, two umbilical cords, Philips head screwdriver, cotton gloves for handling the tubes and appropriately short manual are all included.

Once you unpack the two pieces, you will need to remove the tops of both with the included Philips head screwdriver and place the tubes into the appropriately number sockets. Place the units on your rack, connect the two umbilical cords which are about four feet allowing for a decent amount of placement options, make your connections and plug the unit in. Audio Research has large warnings all over the pieces to never disconnect the umbilical cords with the power supply plugged in - so don't do it.

Audio Research has all critical components custom engineered and manufactured exclusively for them, and supply is tough to get at this level. When I finally got my unit, I wanted so desperately to hear it that I quickly unboxed both pieces, installed the tubes and cleared space on my rack, both by removing the Audio Research Reference 5 preamplifier it was replacing and re-spacing the shelving to allow the power supply chassis plenty of room to breathe. I connected the 40th Anniversary Edition between my Classe-SSP-800 AV Preamp and Krell Evo 403 amp feeding Wilson Sasha W/P speakers and also ran an Oppo BDP-95 and my trusted EMM Labs TSD1 and DAC2 SE combo, both on balanced inputs. All wiring was with Transparent Reference XL for both speaker and audio cables.

I know that break-in is required, and for a piece with capacitors the size of my fists I expected a prolonged break-in. My Ref 5 continued to improve for the first 650 hours. At hour zero I knew it could do better. I ran the preamp for several hours a day and over the first few hundred hours the sound continued to open up and become more spacious and the soundstage deeper. At around 350 hours the sound was really impressive with an ability to pull you into the music and make you feel that you're among the musicians rather than just listening to them.

Now it was time for some critical listening.

I listen to a lot of blues and a recent favorite disc of mine is Son House's Original Delta Blues (Sony). This album is very simple musically but also very powerful. The lone guitar in "Death Letter" had amazing detail and attack, filling the room yet staying well placed. You could hear every detail of the plucking of the strings and feel the texture of the wood of the guitar; it was truly inspiring to hear. The vocals were so clear it felt as though Son House was in my room singing in front of me. "Grinnin' In Your Face" brought chills to my spine with the accuracy of the vocals and the reality portrayed by the hand clapping, the only accompaniment to Son's vocals in the song. The detail was such that you could tell exactly how each hit landed. The slide guitar and harmonica on "Levee Camp Moan" were completely true to life and had amazing weight and depth to them.

Read more about the performance of the Audio Research 40th Anniversary Reference Preamp on Page 2.

Audio_Research_40th_Anniversary_Reference_Preamplifier_Review_angled_stack.jpgI use Tori Amos' Boy For Pele (Atlantic) often as a demo as it contains so many things useful to test a system, fr
om the space of the church the album was recorded in to the power of Amos' Bosendorfer piano and vocals. With the 40th Anniversary Reference, I have never heard the harpsichord in "Blood Roses" seem so powerful yet subtle at the same time. You could truly feel the sound echoing off the walls of the church and Tori's voice was perfect. The piano notes at the start of "Muhammad My Friend" were amazing, exhibiting attack and depth beyond belief while the quiet passages were dead silent; again, you could truly perceive you were in the church where this was recorded and it was the most impressive display of space I have heard in my system.

I listened to Jimi Hendrix's Blues (MCA) disc as I had previously with the ARC's own Reference 5 preamplifier and was amazed at what the 40th Anniversary Edition could do. "Hear My Train a Comin' (acoustic)" had a depth of space that was significantly more than with the Ref 5; the notes were presented with absolute and total control, going beyond ease of presentation into something that was so true to life it was scary. On "Born Under a Bad Sign" the guitar had more weight and depth coming through completely clean and clear. Jimi's voice had an even more natural texture to it and was even a little smoother than with the ARC Reference 5.

I moved on to Rise Against's The Sufferer and the Witness (Geffen Records) to see how well the Reference 40th Anniversary could rock. The bass depth and control on the start of "Worth Dying For" was amazing, even at insane listening levels. While what with another preamp could be a blur of instruments, with the Ref 40th you could easily discern each instrument. The bass control didn't just rival the best solid-state preamps, it was better than the best solid-state preamps I've had. The speed of "The Good Left Undone" was no problem for the Reference Anniversary preamp, and yet still the detail of each component of the song was crystal clear, allowing me to hear details I didn't know were in this song.

The Audio Research 40th Anniversary Edition vs. Reference 5 Preamplifier
When I reviewed the amazing ARC Ref 5 preamplifier, I called it "one of the best preamplifiers in the world" and meant it. I often found myself "lost in the music when listening with it in my system." Then came the 40th Anniversary Edition, which has forced me to reassess. Yes, the Ref 5 is an insanely great preamplifier, capable of doing so many things well, throwing a huge and particularly deep soundstage with exceptional bass control and attack. I recently brought mine to a local audiophile society's 2-channel preamp shootout and despite some serious competition, the Ref 5 was the clear winner of the crowd.

Now, imagine everything sounding even better.

The 40th Anniversary Edition preamplifier has such depth and ease to it, even beyond that of its baby brother the Ref 5. Bass control and dynamics were also better thanks to its quieter background. The sound of the Anniversary Edition is more natural and completely unforced, opening up the music even more and pulling you further into the sound than the Ref 5. This may seem hard to believe if you've heard the Ref 5, but the Anniversary edition preamp is a big leap forward. You get a lot of what makes the Anniversary Edition so special in the Reference 5 preamplifier for less than half the cost, but when you're this far into the stratosphere, improving upon near perfection simply costs more. If you want the best, get the Anniversary Edition, as it is noticeably better in every way to it's little brother - though it's limited production status makes acquiring one easier said than done.

Audio_Research_40th_Anniversary_Reference_Preamplifier_Review_front.jpgThe Downside
It's hard to pick on such a groundbreaking, uber-high-end audiophile component but I will try. To start, the remote is pretty plain, and frankly a touch chintzy for such a high end component. I don't like the machined metal remotes I often find in high-end pieces but the little plastic one in the 40th Anniversary Edition Reference preamplifier is the same one I faulted in my review of their Reference 5 preamplifier. The remote could be a little sturdier and substantial, but it does control all the functions well; it just doesn't look or feel as good as I would like.

The dual chassis design may in some ways also be a negative for some users. Both pieces are large and will need plenty of breathing room to maximize tube life. This will require a good amount of rack space to properly house them. The umbilical cords are plenty long for my system but I am sure some would like to move the two pieces further apart. I have no doubt Audio Research would provide you with any length of cord you desire.

The only real downside to this piece is that by the time you are reading this, you most likely won't be able to buy one - from a retailer that is. Audio Research is no longer taking orders or producing this unit. If you missed the boat, your only option is to search for a used one. I doubt anyone is letting this piece go any time soon. I'd expect to have to pay a pretty dear percentage of its retail cost to obtain one on the used market.

Competition and Comparisons
When you are so far into the stratosphere of preamplifiers, few compete with the Audio Research 40th Anniversary Reference Preamplifier. One obvious comparison is Audio Research's own Reference 5 preamplifier. While just slightly less than half the price of the 40th Anniversary edition, it is available for purchase new and an excellent preamp in it's own right. Another tube preamp that comes to mind is the Doshi Alaap V2.1, which includes a phono preamp as well. One might also like the Cary SLP-05.

Those looking for solid state comparisons might like the Krell Evolution Two or maybe the Mark Levinson 326s. I would also add the Jeff Rowland Criterion preamp to the short list of items to compare this piece to.

For more on these fantastic two-channel preamps as well as others like them please visit Home Theater Review's Stereo Preamp page.

Audio Research Corporation set out to make a preamplifier to commemorate their landmark 40th anniversary and the 40th Anniversary Reference Preamplifier does so perfectly, providing those lucky enough to own one with bass control and depth normally only found in the best solid-state preamplifiers, coupled with subtle tube brilliance throughout the midrange and high frequencies. The depth of the soundstage from this piece is unbelievable; it truly pulls you into the music like no other piece I have ever heard. Top that off with a piece that is near perfectly silent yet exceptionally dynamic; the Audio Research 40th Anniversary Preamplifier is the finest preamplifier made.

I waited over half a year for my preamp to arrive and it was worth every second of the wait. If you can find one, and have the resources to afford it, buy one without reservation. This component is something that costs dearly but its phenomenal sound and the history of Audio Research Corporation's support make it a piece that you will likely never replace. Could you live with an Audio Research Ref 5? Without question and much like those who didn't get in on the Ferrari F40, one would assume there will be 50th Anniversary Preamp down the road but until then, the Audio Research 40th Anniversary Preamplifier is the reference standard for tube preamps and perhaps the entire category of reference grade stereo preamps.

Don't ask me for mine, this piece is not leaving my room until someone peels it from my cold, dead hands as it is without a doubt the best piece of audio gear (not just a preamp) I have ever owned and I am never, ever selling it.

Additional Resources
• Read more stereo preamp reviews by's staff.
• Find a pair of Floorstanding Speakers or Bookshelf Speakers to pair with the preamp.
• Look for sources in our Source Component Review section.

    2015-02-23 05:49:31

    650 hours? Really, explain the nonsense

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