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Actually, dedicated phase monos require just a tiny bit more. "I believe most of our customers won't need to because the standard Merak already exhibits very powerful drive. The 200/400w into 8/4Ω rating is continuous. Peak power is actually 280/900w into 8/4Ω. But for anyone who thinks that 200 watts aren't quite sufficient for an 8Ω speaker in a very large room, bridging two Meraks for one channel quadruples output to 800 watts into 8Ω continuous*3. This requires our bridge kit accessory (<$50). In addition to connecting the inv out XLR—simply a phase-inverted output with swapped pins 2 and 3—of one amp to the standard XLR input of the other via the included very short standard XLR link of the kit, one must install two more jumpers. Those connect the two hot and cold outputs. The -|- jumper simply establishes a shared ground reference. The +|+ is different. It inserts a small stabilizing capacitor for bridge mode. Now you insert the speaker cable's hot lead to the first amp and its cold lead to the second."

*3 As is common MO for bridged amps, the power increase trades for low-impedance stability. A bridged 800-watt pair of Meraks is meant for nominal 8Ω speakers, not 4Ω humdingers with serious dips.

"Merak also includes a defeatable signal sensor. That automatically wakes up the amp from standby with a valid music signal and returns it to sleep mode without. This is a very useful feature particularly with four bridged monos. You needn't turn them off/on one by one. The Plitron mains transformer is very expensive as it had to be very low in profile—less than 57mm in fact—but couldn't exceed a still acceptable diameter. The price for such compacted dimensions was about twice what a standard size equivalent would have cost. Relative to the overall circuit and the number of stages you asked about, the Lundahl transformer acts as input buffer for superior common mode rejection (always better than 100dB). The advantage of an input transformer goes beyond just breaking potential ground loops."

"It also eliminates EMI noise even when the preceding device—preamp, variable-gain source—suffers an output impedance imbalance. Such imbalanced inputs could result in serious CMR degradation with a transistor-based input buffer where in certain cases a just 1% imbalance can lead to a poor 40dB CMR value. Next we completely bypass the UcD 400 board's gain stage to use our own voltage gain stage plus the class A Orfeo buffer feeding the UcD's low-impedance switching stage. You could view this as a 4-stage topology with only the last stage using switching technology." - 王轩骞

The 56.000uF capacitor array represents an energy storage of more than 120 Joule to deliver 16 amps of peak current about equal to 900 watts into large power-hungry loudspeakers says AURALiC.

Kharma's older $6.800/pr MP150 co-designed by Bruno Putzeys with modified UcD board and linear power supply

To recap, AURALiC's Merak introduces a transitorized twist on a theme Mark O'Brien's Rogue Audio Medusa [right] and Hydra amps sang at CES 2012. The two rogues mate a Hypex UcD 400 module with bypassed gain stage to custom tube gain and a linear power supply*4. Merak's tube equivalent becomes the class A Orfeo buffer preceded by a Lundahl input transformer. But the concept of exploiting UcD just for its switching output stage whilst avoiding an SMPS in favor of a burly linear power supply are shared. Merak thus becomes the rogue of Hong Kong. The catalogue of AURALiC now spans four half-width components: a DAC, two headfi/preamps and a pair of mono amps.

*4 There are also the ICEpower-based H2O Audio amplifiers from Mr. Ho which combine B&O modules with absolutely massive linear power supplies.

AURALiC mods. "This is the test result from the original Hypex module and our improved one. Whilst we did sacrifice THD by 6dB, we reduced all 4th to 9th higher-order harmonic distortion by a remarkable level. This is a key reason why Merak sounds different from other switching amplifiers." - 王轩骞

From the comfort of my arm chair I'd long wondered why the rise of ICEpower amps hadn't been challenged by Hypex competition. The latest D class Pacific Rim amp I'd hosted had been Simon Lee's ice'd Eximus S1. Competing for the same customer, AURALiC now suggested that we go Dutch with Bruno Putzeys' Hypex/UcD, albeit only partially and then clearly modified. In this steadily growing segment I was keen on hearing how the other half lived.