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Accuphase E-550 Integrated Amplifier Review

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Accuphase E550 Angle Integrated Amplifier

The subject of this review is the Accuphase E-550 line-stage integrated amplifier.

The phase-accurate Accuphase of Japan has been producing award-wining amplifiers since its founding in 1972, and that majestic power meter in gold chassis design has become the arresting visage of all Accuphase amplifiers shortly after. In fact, Accuphase believes that there will be adverse consequences if they are to ever market an amplifier nowadays sans that proven façade design. See the Dagogo Commentary, The Accuphase Culture.

The enduring Accuphase cosmetics are only one of the more immediate attributes contributing to the company’s success; engineering ingenuity is also a much-proven and respected facet of Accuphase. Accuphase’s past power amplifiers, a series that numbers a staggering total of 32 of them, generally have a lifecycle of four to five years before they are replaced, with a few designs that enjoyed up to nine years of production run. In addition, the specialty audio company also introduced 24 integrated amplifiers, 22 preamplifiers, 12 CD players, 10 tuners, 3 reference CD transports, 4 reference DACs, 1 digital equalizer, 1 digital preamplifier and a sleuth of other products of such enormous scope that underscores the company’s engineering prowess, as well as belies its modest operations.

That was just the past. In present day, Accuphase’s current series of products encompass 6 power amplifiers, 4 preamplifiers, 4 integrated amplifiers, 2 power supplies, 2 digital crossovers, 2 top-grade SACD/CD players, 2 CD-only players, 1 top-grade SACD/CD transport, 1 top-grade SACD/CD DAC, 1 digital tuner, 1 digital equalizer, plus a series of home theater components and other accessories. Did I miss anything?

The busy minds at Accuphase must be enjoying what they are doing, and they don’t seem to be taking vacations.

Accuphase’s approach to product construction and engineering is unusually methodical and organized. The engineers’ conception of the three principal sections in the E-550’s makeup, namely the input/output, power supply and amplification, took on a new dimension in measures.

On The Accuphase Analog Vari-Amplifier

In the midst of all this impossibly meticulous arrangement are Accuphase’s two eminent engineering feats: the Accuphase Analog Vari-Amplifier volume control and the Multiple Circuit Summing+ topology.

The Accuphase Analog Vari-Amplifier volume control, or AAVA, is the company’s vision to the universal quest for constant-impedance in all volume settings. The AAVA technology as executed in the E-550 is a scaled-down version of the technology as implemented fully in the company’s flagship preamplifier, the C2800. The AAVA process converts incoming voltage into the current domain and funnels it through 16 current –voltage amplification switches with full balance control functionality, thus negating the need for the deleterious variable resistors in traditional attenuators. Then, a CPU onboard detects changes in current value as initiated by movements on the big volume knob, and with 65,536 setting possibilities, Accuphase claims that “operating the knob therefore feels exactly the same as with a conventional control”. I found that statement to be entirely correct, although it doesn’t begin to describe the rare, remarkable sense of assurance and satisfaction that I obtained from operating the very solid and smooth large dial every time.

My experience with the Accuphase AAVA in the company of the Linn Klimax Chakra 500 Twin also proved most gratifying. Linked to the Accuphase’s PRE OUT RCA jacks via the Furutech Audio Reference III RCA, the Linn’s winning suits of generous dynamic transients and immaculate resolution were lively preserved in reproducing a wide variety of music, and most evidently in the reverberating and syrupy rendition of soprano Elly Ameling’s alluring and divine portrayal of Edvard Grieg’s Anitra in the “Arabian Dance” (Peer Gynt Op. 23, Philips). If performance of the E-550’s AAVA implementation can make music sound so enjoyable, then I can only imagine the level of fidelity as brought forth by the flagship C2800 preamplifier.

On Multiple Circuit Summing+

Complimenting this advanced engineering feat is the Multiple Circuit Summing+ topology, or MCS+.

While Accuphase rates the output of this topology in the E-550 as 30watts per channel at 8Ω, it also declares a 1Ω output capacity of 150watts per channel! The MCS+ is a refinement of the class A-biased circuitry in the original MOSFET MCS topology for greater stability and noise reduction. This concept involves taking a class A-biased push-pull topology and tripling up the MOSFET-based arrangement for intensified current delivery capability. The MCS+ also carries all signals from input to output in balanced mode to attain excellent Common Mode Rejection Ratio.

Although the E-550 is rated as putting out 60watts into a 4Ω load when driving the $12k, 89dB/4Ω GamuT L5 loudspeakers, repeated listening with a decibel meter showed that the integrated amplifier was able to compel the Danish speakers to produce a frighteningly high sound level approaching 90dB within my 12 x 27 x 8 listening room. At that stage, the Accuaphase continued to sustain solid, unwavering composure at the bottom-end, complete with a top-end sounding just as serene and silky as that produced by the $11k Audia Flight 100 power amplifier that I reviewed in October 2005, conceding comparatively to the Italian behemoth’s ultimate domination in power and scale as sustained by the dual-700VA-toroidal and 32-IBGT armament.

Yet, when the Furutech Audio Reference XLR interconnects was feeding the Accuphase with signals from the full-volume Wadia 27ix v3.0 Decoding Computer’s XLR out, the upper midrange to the top-end of the contemplative Japanese fue and its accompanying taiko from “Snowy Morning (Yuki no Ashita)” of the JVC XRCD disc, Dotou Banri, was full-sounding and extended. The level of contrasting dynamics, and the lack of textural artificiality and tonal exaggeration on the taiko-accompanied lone woodwind represented the most sonorous reenactment I have ever heard from anything below $15k, next to the $18k Audia Flight PRE and 100 solid-state amplification system.

In reproducing the playing of a quadruplet of taiko’s from elsewhere in Dotou Banri, the Accuphase-driven GamuT L5 was then propelled with such exuberance to produce powerful displays of colossal confidence and enduring vigor, giving full acknowledgement and credit to this most powerful of traditional instrument demonstration disc. In traversing the CD, the E-550 showed no sign of compression or distortion in controlling the GamuT, with seemingly unlimited supplies of current.

The one imperfection amidst all my elations was the very traditional On/Off design sans Standby. Consequently, the E-550 would require a good hour’s time to get to being in the top form from cold start.


Appearance-wise, I think the E-550’s champagne gold façade as adorned by the twin power meters and a knob on each side of the display window, is of the most complete implementation of the “Accuphase look” among all other Accuphase products. Get one of their four preamplifiers, and you get the big round knobs and display window sans meters; or you can get their power amplifier with big meters but no knob. Get it?

Seldom has any equipment acquired a look so assuring and attractive that conjures up ownership craze instantly.

On the gorgeous knobs, the left knob labeled INPUT SELECTOR has gem-sized LEDs embedded onto the outer ring that lights up to indicate the selected source, such as, clockwise from the left, LINE 2, LINE 1, LINE-BAL, CD-BAL, CD, TUNER, OPTION 1, OPTION 2. The POWER switch sits below this knob. The right knob is the VOLUME, beneath which sits the ATTENUATOR button that truncates the volume by 20dB.

The wide display window contains the two power meters, plus an underlying array of indicators for small-knob functions accessed in the concealed sub panel underneath, such as, from left to right, SPEAKER (OFF, A, B, A+B), COPY (1→2, OFF, 2→1), and RECORDER (REC OFF, SOURCE, 1, 2). At the middle of the sub panel are a top and bottom rows of push-buttons, such as MC/MM, ON MONO, ON COMP on the upper row, and EXT PRE ON, METER OFF, TONE ON on the bottom row. Then, a symmetrical array of a triplet of small-knob occupied the right portion of the sub panel, such as BASS, TREBLE and BALANCE.

A feature of the E-550 that audiophiles will never use, the tone controls did not impose audible distortions in operation. With an operating frequency of 300Hz for the BASS and 3kHz for the TREBLE, each tone control allow ±10dB of adjustment, and I discerned no deleterious manifestations in resolution in their operation. Practically speaking, in using the E-550, one is unlikely to come into simultaneous possession of loudspeakers with a coinciding dip or peak at the exact frequency points that can benefit from the E-550’s BASS and TREBLE adjustments, although the use of the BASS control will yield a fuller sound when listening casually at low output levels.

Movements of the E-550’s meters were indiscernible from my listening position 9 feet away, so I turned them off for the most part, although doing so never yielded additional sonic benefits.

Finally, each of the Accuphase’s RCA and XLR jacks was protected meticulously by its own cap, a most thoughtful arrangement I haven’t seen on any other company’s equipment to date. And the speaker terminals featured the largest of binding posts I’ve seen, fully accessible to the most endowed of bananas or spades.

Even the E-550’s feet are of “high carbon” cast-iron insulation to dampen vibrations.

The complimentary remote, RC-200, provided access to source selection and volume control, and yet the omission of a Power On/Off functionality on a $10k Accuphase product is unfathomable.


Having witnessed the E-550’s delicacy and prowess, I question not Accuphase’s extraordinarily conservative stance in rating its amplifiers’ output, but the degree to which we are being led to underestimate the real potentials of the integrated.

The necessary survival criteria for a high-end integrated amplifier center on its potentiality and practicality. Since an integrated amplifier negates the freedom of gradual upgrades, audiophiles are oftentimes reluctant to consider the costlier of the kind. Hence, any integrated amplifier carrying a price tag of $9,995 will draw imminent scrutinies on its ability to surpass similarly priced systems of preamplifier and power amplifier.

Yet, being an Accuphase design, the E-550 was not merely a class-setting integrated design, it also possessed an advanced preamplification stage and a refined power output stage that were designed to function separately for latter connection to an external power amplifier or preamplifier. Hence, serious audio fun begins at the E-550 and seemingly has no end.

Readers now planning on spending $10,000 for a complete preamplifier and power amplifier system will experience utter excitement once he or she has heard the Accuphase E-550.

The Accuphase integrated amplifier marks the latest evolution in Accuphase’s remarkable product development history. In its indigenous local market, Accuphase is recognized as the premium audiophile-grade specialty firm among the likes of conglomerates, such as Denon, JVC, Kenwood, Marantz, Sony, Teac (Esoteric) and Yamaha. Senior audiophiles in Japan liken Accuphase to brands like Altec and JBL, while younger generations are quick to compare Accuphase with the likes of the American Krell and the British Linn.

In contrast to the marketing strategies of the industry’s corporate citizens, Accuphase has proven to pursue and preserve the preferences of audiophiles in search of the utmost in quality. This level of corporate identity demands a most visionary R&D and marketing efforts to sustain its long-term success in the marketplace, and it was with this level of commitment that it succeeded in persisting upon a track record of innovation and value.

With the E-550, Accuphase has done it again.

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