Pros: Simple, indestructible, inexpensive, does exactly what it claims to do
Cons: I wish there was a model with two headphone jacks
Skip to 2008, when I found myself buying multi-hundred dollar headphones—such as the Grado 325 and AKG K 701—and running them with dedicated headphone amplifiers, mostly pro-audio "headphone distribution amps," nothing overly fancy. I also found that some pro mixing boards did a great job of powering headphones—I became a fan of Alesis gear for that reason. The quality I achieved was good enough for me, and I enjoyed five great years of listening to a rig that consisted of the AKGs and a Presonus headphone amp.
A few weeks ago, I was browsing Stereophile.com, and an article caught my eye. It described a $79 box called the Can Opener—made by a company called Vinyl Flat LLC—which connects to an amplifier's speaker terminals and provides a quarter-inch headphone jack. The premise: if you attenuate the signal coming directly from a speaker amp or AVR, it effectively turns that device into a headphone amp. This sounded perfectly reasonable to me, so I placed an order right away.
Three days later, I had my Can Opener in hand. For a metal box, it looks better than expected. It is as minimalist as it gets, with a pair of speaker terminals on the backside and a Neutrik locking quarter-inch headphone jack in front. The box itself is indestructible and measures about 4x4x1 inches.
It's a nice, minimalist metal box.
I have a retired receiver that I wanted to dedicate to the Can Opener—a Pioneer VSX-522, which sells for about $200 new—nothing fancy.
The results immediately blew me away. I have a number of great pairs of headphones, and the Can Opener produced better sound through all of them compared with any and all of my existing options. The sense of transparency and realism coming from the AVR was akin to a multi-hundred dollar "audiophile" headphone amp/DAC combo. Not a multi-thousand-dollar rig, mind you—but definitely in the $300-500 range, which is not that far from the actual cost of the headphone station I put together. The difference is that I only had to spend money on the Can Opener to get that level of performance because I had a spare AVR.
The VSX-522, serving as a headphone DAC and amp, thanks to the Can Opener
My main system is based on a Pioneer Elite SC-55, which has better DACs and better amplification than the VSX-522. Since my mains are self-powered, I do not use the speaker outs on the Elite. One of the main reasons I bought the Can Opener was to use ultra-high definition headphones to listen to different amps and AVRs with a constant frame of reference. There is much debate about whether amplifiers/AVRs sound different or not, and I figured that the Can Opener could be helpful in determining that.
I decided to go straight to some classical—Mozart's Violin Concerto No. 5 with Itzhak Perlman and the Philadelphia Orchestra (20th Century Masters—Millennium Collection, remastered ©2005 Universal). It was as if my Pioneer SE-A1000 headphones totally disappeared, leaving only the music. The same track played from an iPad with the headphones plugged in directly sounded considerably more congested, less ethereal. It was much easier to get lost in the music when using the Can Opener, even driven by a modest AVR.
I could not hear much difference between the sound quality coming from the VSX-522 and the SC-55 AVRs. Both Pioneer receivers evidently had more than enough power in two-channel "pure direct" mode to allow the Can Opener to work well with my headphones, even when splitting the signal and powering two pairs of cans.
While the Pioneer SC-A1000 is a revealing headphone, the AKG K 701 goes even farther in terms of fine detail rendition at mid and high frequencies; I do not prefer it to the Pioneers, but I respect its capability. Listening again to the Mozart had me realizing that AKG is batting for the home team when it comes to reproducing this genre of music. The K 701 is tougher to drive than the SE-A1000, and the extra power that the Can Opener taps into brought out the best I've heard from those cans.
Pioneer SE-A1000 on the left, AKG K 701 on the right
I decided to take the K 701 for a genre-hopping tour through my music collection. If the Can Opener could make me love the K 701 again, that alone would justify the purchase—because the AKGs cost four times as much as the Can Opener.
GZA's 1995 album Liquid Swords sounded utterly crisp, the Wu-Tang production coming though with the same transparency I experienced in the classical-music experiment. The K 701's bass remained slightly lean for my taste, but the soundstage had a tangible quality that reminded me of real speakers, not headphones. I felt a compulsion to plug the Pioneer cans back in; the reward was a better bass thump, yet the crystal clarity remained.
What was I to do? Full disclosure: I now listen to the Pioneer SE-A1000 all the time, and I bought three pairs of them. They are tremendously revealing and on clearance, they represent a nearly unbeatable value—check out my review.
The next logical step was to build a separates-based listening station. I am no fan of audiophile prices, and I feel that pro-audio gear often offers the most bang for the buck. As a result, I have some spare pro gear that I was able to repurpose. I combined a Roland Quad-Capture audio interface (DAC) with a Crown XTi-1000 amplifier and the Can Opener. The next few nights of listening sessions with my wife wound up being among the most profound listening experiences I have ever had.
The Crown XTi-1000 based headphone station.
The value of a good DAC and a good amplifier cannot be overstated. My initial impression is that AVRs really do sound similar to each other, be it a $200 or a $2000 model. Power output may vary, but the sonic signature remains. A dedicated DAC and amp is the preferred approach among audiophiles, whether they are running speakers or headphones. I have long understood the value of this approach for speakers, but now I can see the value as it relates to headphones.
The amp-powered Can Opener and SE-A1000 combo introduced a crystal clarity to music reproduction that was missing from all the other sources at my disposal. The improvements in sound were on both ends of the spectrum—bass was tighter and deeper, and highs were crisper and more ethereal. I repeatedly heard fidelity I usually associate with esoteric systems that I simply cannot afford.
It was time to test another headphone, one that I use all the time, but usually with my phone, not at home. The Creative Aurvana Live!—also known as CAL!—is my favorite low-cost sealed can, and it sports Denon drivers that produce a balanced, dynamic sound and rather satisfying deep bass. Would the same magic I heard with the Pioneer and AKG make another appearance? Absolutely—I went for some of the most intense and bass-rich tracks in my library, only to find a willing accomplice in the CAL!, which I now respect more than I did. I can specifically point to "Adagio for Tron" (remixed by Teddybears)—a favorite deep bass reference track of mine—as proof that the performance of the Creative headphones was enhanced well beyond what one would get by plugging them directly into a receiver.
A "Can Opener" indeed—that little black box is actually a radical transformation of how I listen to music. Peeking inside, all I saw was four resistors mounted on a tidy little circuit board. I suppose that's all it takes to convert a high-quality speaker amplifier into a high-quality headphone amplifier. Although I can highly recommend using the Can Opener with a retired AVR, it truly shines when paired with the best amplifier you can connect it to. For anyone who happens to have a spare amplifier, I can think of few things that will offer more bang for the buck in terms of audio satisfaction. I look forward to auditioning higher-end amplifiers in the future by taking the Can Opener on the road with me.
Here is a chart with a level-matched measurement from the headphone jack on the Pioneer, versus the Can Opener. The Roland Quad-Capture is the DAC for both measurements. Each measurement is the average of four sine sweeps, using REW. The main thing to note is the Can Opener's bass response is slightly flatter, and the treble is slightly brighter. The differences are minor—around 1/2dB maximum, but it affects the presentation enough to hear.
Measurement taken from headphones
Direct measurement of output. The Can Opener shows a flatter response.
As subtle as the differences might be, the Can Opener's resistors do not produce identical results to what's inside an AVR