Reviewer: Srajan Ebaen
Source: Cairn Fog v2.0 as transport; Zanden Model 2000 as alternate transport [in for review]; Zanden Audio Model 5000 MkIII DAC; Furutech Digi. Reference BNC-BNC digital cable; Ortho Spectrum AR-2000 filter/buffer on the DAC's analog outputs
Preamp/Integrated: Bel Canto PRe6 GenII; Eastern Electric MiniMax [in for review]; ASL MGHead DT/OTL 32 [in for review]
Amp: AUDIOPAX Model 88; Bel Canto eVo 4 GenII; Coda Technologies S5 [on review]
Speakers: Avantgarde Acoustic DUO; nOrh SM 6.9; Gallo Acoustics Reference III
Cables: HMS Grand Finale; Analysis Plus Solo Oval and Oval 8; i2digital X-60; Stereovox HDXV; Mapleshade Ebony active digital interconnect; Mapleshade Planar power cord with DC bias; Audio Magic Clairvoyant power cords; Z-Cable Reference Cyclone power cords on powerline conditioners; Crystal Cable Reference interconnects, speaker cables and power cords; Stealth Audio Cables Indra [in for review]
Stands: Grand Prix Audio Monaco four-tier
Powerline conditioning: BPT BP-3.5 Signature; Walker Audio Velocitor for source components
Sundry accessories: GPA Formula Carbon/Kevlar shelf for tube amps; GPA Apex footers underneath stand and speakers; Walker Audio SST on all connections; Walker Audio Vivid CD cleaner; Furutech RD-2 CD demagnetizer; WorldPower cryo'd Hubbell wall sockets; Musse Audio resonance dampers on DUO subs; Mapleshade 4" solid maple platform under BPT conditioner
Room size: 30' w x 18' d x 10' h [sloping ceiling] in long-wall setup in one half, with open adjoining living room for a total of
ca.1000 squ.ft floor plan and significant 'active' cubic air volume of essentially the entire (small) house
Review component factory-direct pricing: 999 Euros for Pre Two; 1749 Euros for Enigma Plus; 125 Euros for door-to-door DHL delivery
The original launch of Toccata Industry's groundbreaking TacT Millennium amplifier topology, since then acquired by cor-porate giant Texas Instruments, was shortly followed by Bel Canto Design's Tripath Digital Power Processing implemen-tations. These two events stand out in memory as marking the turning point when pulse-width modulated 'linear' amplification architectures started to openly make inroads into high-perfor-mance consumer audio. Broadly referred to as Class D, this amplifier concept initially saw its widest use in subwoofer plate and car audio amps where efficiency and small size were more important than ultimate sonic performance.


Akin to how 47lab's famous GainCard circuit sanctified the employ of 'lowly' op-amps as uncompromised speaker-level output devices, the appearance of the Millennium and eVo amplifiers rewrote limiting perceptions, rules and expectations for 'digital' HighEnd amplifiers. Linn's Klimax (which, despite perceptions, actually is a Class A/B amp with switch-mode power supply), Sharp's flagship 1-bit amplifier, John Ulrich's Spectron Musician, Audio Physic's monos, Chapter Audio's Chapter 2 and ongoing newer introductions like Audio Research and Chateau Research then added -- and continue to add -- further cache and recognition in this field. In parallel, exploding Tripath iterations, Sony's proprietary digital amplifier modules and Yamaha's Flying Mole variants have invaded and converted the volume sector of so-called MidFi products while LC Audio from Denmark is introducing models under their own name as well as DIYCable's Exodus brand.


Yet another emerging entrant into this arena is Bang & Olufsen's cannily christened ICEPower. For ultra-performance duties, it has already been embraced by Jeff Rowland, our review's Peter Thomsen of Danish firm Acoustic Reality and, I'm told, by at least three other firms who prefer to keep their use of ICEPower as low-profile as possible. If this trend continues, stalwart champions of traditional non-linear Class A topologies like Krell and Classé could one of these days find themselves outnumbered and outmuscled by this new breed of high-efficiency switch mode amplifiers.

ICEPower was jointly engineered by B&O and the Technical University of Denmark. The Acoustic Reality implementation replaces more than 20 devices of the original ICEPower module in a proprietary modification to improve sonic performance. Specs include power supply noise suppression by 60dB for a final S/N ratio of 120dB; 5Hz-90kHz bandwidth; 30dB of gain; and what is claimed to be one of the lowest amplifier output impedances extant, hence equating to very high damping factors. In a call from Denmark -- whose entire national telephone structure, I learned, is owned by one US firm, making transcontinental calls cheaper than the domestic mobile network -- Peter Thomsen explained that his amplifier topology is completely stable into 0.6 ohms.
The following technical descriptions -- about how ICEPower differentiates itself according to its engineers from other Class D architectures -- are far beyond my personal capacity to comprehend and thus comment upon. They're provided here solely for comprehensiveness' sake and for those readers technically inclined. They were transcribed from an e-mail that Peter Thomsen submitted for this specific purpose. To wit and as claimed:


The ICEPower analog technology is based on two new methods, the COM modulator and MECC feedback control technique. The COM modulator is at the heart of the ICEPower platform and represents a new modulator class with distinct advantages over classical PWM and Sigma-Delta/PDM methods. The Controlled Oscillation Modulator (COM) is a higher-order feedback loop forced into controlled instability, taking full advantage of the programmed oscillation frequency for modulating the switching, high-efficiency output stage. The characteristic signals of the COM are illustrated below and benchmarked against classical PWM and PDM/Sigma-Delta type modulation methods.

Versus traditional methods, this particular COM implementation is said to provide more precise modulator performance by comparing its sinusoidal modulating signal against zero whereas PWM systems use a triangular signal which is difficult to generate, distorts and is compared against "a noisy feedback signal". The transfer function of this COM modulator is independent of the power supply variable Vs, hence makes for a theoretical power supply ripple rejection or PSRR value of infinity. PWM acts as perfect multiplier for the input and power supply signals to not provide any power supply rejection capability. Because the COM is programmed for instability, it can't go unstable. Unlike digital PWM methods and Sigma-Delta methods, the ICEPower COM doesn't generating quantization noise and thus readily achieves a dynamic range of 115-120dB. Besides being a modulator, the COM also acts as an ultra wide-band, cycle-to-cycle feedback control system to dramatically improve distortion, intermodulation and dynamic performance. The COM modulator is the simplest possible topology, e.g. simpler than PWM since it doesn't require a precision triangular carrier generator. It spreads its HF energy to ease application design for EMI approval. The COM modulator's switching frequencies typically operate between 80kHz - 400kHz. Low switching frequencies at high output currents secure a better efficiency than fixed-frequency PWM and significantly better efficiency than the very high-frequency Sigma-Delta/PDM architectures.
COM signals with the sinusoidal modulating signal [central figure]
The second and equally important novel part of the ICEPower topology is the Multivariable Enhanced Cascade Control MECC technique which implements a powerful feedback control system around the COM modulator.

MECC calls itself "a practical method for higher-order control system realization especially developed for the characteristics of switching output stages including passive demodulation filtering. The topology enables powerful control of all important audio parameters like distortion, noise, frequency response and output impedance. The output filter has traditionally been (and still remains) one of the main limitations of sound quality and overall audio specifications in Class D amplifier designs no matter the approach (analog or digital modulation, PWM or PDM). Furthermore, the output filter adds significant output impedance and limits the amplifier bandwidth/transient response". The merits of MECC are listed as follows: PWM amplifier damping factors are generally limited to 10-50 especially at higher frequencies, this due to the passive LC filter and the power stage output impedance. MECC enables damping factors in the range of 2000-5000 and very stable frequency response independent of loads. The output filter of traditional implementations "inevitably affects specifications and sound quality" for which MECC, by contrast, is said to "powerfully correct".
Translated into everyman's English, the above highlights indicate that ICEPower uses multiple internal feedback loops and an output filter that's nested inside rather than outside these loops. The spread-spectrum Tripath switching band is 200kHz - 1MHz and thus above the Danish 80 - 140kHz while the controlled instability of the ICEPower COM modulator at least conceptually seems related to the chaos modulator in Audio Physic's patented digital high-power monos.


This miniature primer on ICEPower (in the end, what it sounded like would be the real issue) was followed by another one of Peter's e-mails. This one was about a new ribbon-based line-source speaker module. He already has received outright patent purchase offers for it, indicating that we're looking at a radical new transducer solution whose advantages seem blatantly obvious to competing design houses. Acoustic Reality's ICEPower amps will be mandatory for these new speakers whose impedance behavior recalls Jason Bloom's amp-eating Scintillas of yore. Peter further informed me that he just signed up an Acoustic Reality distributor for America:

ProLink Distributors, 1448 Ford Road, Bensalem PA 19020, (484) 919-8618


The review model Enigma Plus amplifier will remain Internet-direct to maintain its price. The eAR Two Plus stereo [$6,200], eAR One Plus monos [$9,300/pr], Extreme stereo [$16,500] and Extreme monos [$22,000/pr] will be handled by ProLink through their own Bensalem/PA showroom and a to-be-built domestic dealer network.


ProLink will also represent the new Acoustic Reality line-source speaker which has been dubbed Q-Art. It carries a most serious retail price of $60,000/pr but includes: A pair of diamond-glass sealed ribbon panels [above]; a 10" subwoofer with twin 10" passive radiators (all sourced from ScanSpeak's new 23W series); an active and adjustable crossover network; one three-channel silver-wired ICEPower Extreme amp with 500 watts to the subwoofer and 250 watts each to the ribbons. Bill Harris of ProLink already offered us a follow-up review of one of the dearer Acoustic Reality amps. Thus, and to paraphrase Ed Harris' short hand to his ex-wife in The Abyss - "keep your panties on".

Named perhaps after the infamous German U-boat cipher to infer some kind of aural code breaking to parallel the Allieds' legendary breakthrough, the affordable new eAR Enigma Plus power amplifier incorporates experience garnered from the development of the firm's cost-no-object MkII incarnations of their eAR One and eAR Two models. Duplicating the smaller Two's power rating of 120/250wpc into 8/4 ohms, the Enigma version eschews the former's balanced XLR inputs, replaces its WBT terminals with Speakons and halves the size of its capacitor bank and power transformer.

The choice of Speakons, though electrically and mechanically far superior to the ubiquitous spade/banana interfaces, made it necessary to request adaptors with standard binding posts since none of my speaker cables are terminated with Speakons. Connections are made in a slightly crammed bay underneath the rear corner of the triangle enclosure.

Footers with integral bearing decouplers as well as spikes were provided; ditto for a Cryophon power cord and Kema SSP-630 industrial polish stainless steel cleaner. Measuring 15 inches along each side of its equilateral enclosure, the Enigma with blue power LED stands roughly 6.25" tall depending on chosen footers. The matching non-remote eAR Pre Two in its petite 'leaning pyramid' stainless casing is usually outfitted with three inputs. For review purposes, it was dispatched with Acoustic Reality's optional Q-Controller to evaluate the latter's tuning effects on ported speakers. To increase performance of such designs -- I'd use my super-robust nOrh SM 6.9s -- Peter recommends stuffing their ports while dialing in superior in-room bass response via the small twin knobs on the Pre Two's rear. The large knob on the back would select between inputs 1 and 2 while the third set of RCAs was the direct, the right-most one the Q-controlled output - ideal for reviewer-style aba babas. The triangular Pre Two measures 8.75 inches on its longer front, 6.5" along the volume control face and 9.25" on the rear. 5 inches of height to the top point include the small rubber bumper feet. The aft 5-pin port connects to a two-prong 6' umbilical with integral +/-17V AC-to-DC wall-wart power supply.


All in all, my first eyes-on encounter with ICEPower proved to be a most skillful aesthetic interpretation of the subliminal suggestions embedded in the moniker - cool chic Scandinavian flair, translated as frosty stainless steel, bent and folded into attractive geometric shapes of wild departure from the ubiquitous rectangular boxes. The somewhat inconvenient connectivity issue encountered was clearly in the service of elegant appearance. It won't be a bother for regular users who don't constantly swap out components and cables (that very under-appreciated, unglamorous element of professional reviewing). Still, I highly recommend flipping Enigma upside down and making all connections before inserting it into your chosen equipment rack. Getting especially the power cord and interconnects into their respective positions afterwards turns into a major conniption fit. And just-fed Anaconda interconnects and power cords plain won't work, period.


One other design flaw in the Enigma is the absence of protection circuity. Short an output and said channel will go poof. Of course this absence is accompanied by the usual appeal - it sounds better this way. Personally, I'd rather use protection than father a flaming accident. Hence I call this feature -- or non-feature as it were -- a serious flaw.

In preparation for the anticipated question -- how would ICEPower compare to Tripath? -- I requistioned the latest-generation eVo 4 from Bel Canto's John Stronczer who cheerfully responded. Replacing my older 200.4 with a current eVo 4 GenII, I was told that most everything outside the visibly new fascia had been upgraded as well. This included two of the latest Tripath processing and driver mother boards, new 4-layer circuit boards and a beefier power transformer. I also had my PRe6 upgraded to GenII status via a new unit and will, in an upcoming feature, report on the differences with the genI version which I shall retain just long enough for this comparison.


I now felt properly set to enjoy two flavors of digital amplification in their respective best lights, although in fairness, it bears repeating that Acoustic Reality does produce amplifiers far above the Enigma if cost weren't an issue. For the direct A/B, I'd use two unbridged channels of the eVo 4 for equivalent 120wpc output. I'd run either amp first off the PRe6, then the eAR Pre Two, both in single-ended hookup (the preferred connection between PRe6 and eVo is otherwise balanced) to evaluate the Acoustic Reality preamp vis-à-vis the more expensive 6-channel Bel Canto unit in even-handed fashion.