Description: Solid-state, class-D, remote-controlled integrated amplifier. Power output at 1kHz: 85Wpc into 8 ohms (19.3dBW), 0.5% THD. Frequency response: 10Hz–60kHz, +1dB/–3dB (CD). THD: 0.08% (1kHz, 1W). Damping factor: 25 (1kHz, 8 ohms). Signal/noise ratio: 100dB (CD, IHF-A), 70dB (phono, IHF-A). Input sensitivity and impedance: 200mV, 50k ohms (CD); 2.5mV, 50k ohms (phono). Recommended speaker impedance: 4–16 ohms. Power consumption: 110W (0.3W in standby).
Dimensions: 17 1/8" (435mm) W by 5 13/16" (148mm) H by 16 15/16" (431mm) D. Weight: 28.7 lbs (13kg…
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Sidebar 1: Specifications
Sidebar 2: Associated Equipment
Analog Source: Linn LP12 turntable with Lingo power supply, Linn Ittok tonearm, AudioQuest AQ7000 nsx cartridge.
Digital Sources: PS Audio Lambda II CD transport; Perpetual Technologies-ModWright P-1A/P-3A digital processors with Monolithic Sound P3 power supply.
Preamplification: Bryston TF-1 step-up transformer.
Integrated Amplifiers: PS Audio GCC-100, Flying Mole CA-S10.
Loudspeakers: Avantgarde Acoustic Uno 3.0.
Cables: Digital: Mystic Reference I2S, Illuminati Orchid AES/EBU. Interconnect: PS Audio xStream Statement. Speaker: Nordost…
Sidebar 3: Measurements
Looking first at the Onkyo A-9555's phono stage, this was suitable for moving-magnet cartridges, with a voltage gain a little lower than normal of 35.6dB (measured at the amplifier's Tape Out jacks) and an input impedance of 45k ohms. The RIAA equalization featured a treble region that was shelved down by 0.75dB (fig.1), which will be audible as a slight dulling of the balance. The two channels matched very well, however.
Fig.1 Onkyo A-9555, phono-stage RIAA error at 5mV input at 1kHz (0.5dB/vertical div., right channel dashed).
The phono…
How much amplifier power do you need? Most audiophiles figure a maximum of a few hundred watts per channel—beyond that, you're wasting your money or showing off. Others think that anything more than a few watts will mess up an amplifier's musical coherence or "purity," so they stop there and find uncommonly sensitive speakers, usually compression horns with cone woofers.
Of course, how much power you need depends on how much realism you seek. If you want only background music, or a pleasant but subdued version of the real thing, perhaps you don't need that much power. However,…
There are peripheral issues. To get the most from the Supercharger, you need more expensive jumpers and AC cords than the ones supplied, but these are minor costs. I used the supplied jumpers, along with my reference Shunyata Research Helix Anacondas.
Let's play!
First up was the 100Wpc Music Reference RM-200, my reference tube amplifier and a reasonably priced, rugged, ultra-reliable component. JA's measurements, which accompanied my review in the April 2002 issue, showed that the RM-200 delivers 95W via its 4 ohm tap at 1% distortion. It can drive the 92dB-sensitive Wilson Audio…
Sidebar 2: Specifications
Description: Solid-state, monoblock power amplifier with line- and speaker-level inputs. Maximum power output: 550W into 8 ohms (27dBW), 750W into 4 ohms (25.75dBW). Maximum output voltage: 66V RMS, 20Hz–20kHz; 186V peak–peak. Maximum current: 250 amps peak–peak. Frequency response: 20Hz–30kHz, +0/–0.2dB. THD+noise: <0.016%, 20Hz–20kHz. Damping factor: 220. Input impedance: 50k ohms (line), 50 ohms (speaker). Input sensitivity for full power out into 8 ohms (line): 2.23V, speaker 33V. Signal/noise (no reference level quoted): >120dB (line input), >115dB…
Sidebar 2: Associated Equipment
Analog Sources: Continuum Audio Labs Caliburn, Grand Prix Audio Monaco, Merrill-Scillia Audio MS-21 turntables; Continuum Audio Labs Cobra, Graham Phantom, Tri-Planar tonearms; Lyra Titan i, Air Tight PC-1 cartridges.
Digital Sources: Musical Fidelity kW DM25 DAC & CD transport, Esoteric SA-60 universal player, Musical Fidelity X-RayV8 CD player, BPT-modified Alesis Masterlink hard-disk recorder.
Preamplification: Manley Steelhead, Einstein Audio Turntable's Choice phono preamplifiers; darTZeel NHB-18NS preamplifier.
Power Amplifiers: Musical…
Sidebar 3: Measurements
Before performing tests on an amplifier, I thermally stress it by running it for 60 minutes at one-third the specified power into 8 ohms, which is the worst case for an amplifier with a class-B or-AB output stage. Eyeballing the Musical Fidelity Supercharger 550K, it doesn't appear to have enough heatsink area for a 550W design. This, in fact, proved to be the case—it shut down after 18 minutes of operation at 191W into 8 ohms. The chassis was way too hot to touch and the amplifier's orange Temperature LED was illuminated. Letting it cool down for 30 minutes…
Erick Lichte reviewed the 550k Supercharger in December 2008 (Vol.31 No.12):
Back in May, my vocal ensemble, Cantus, gave a series of concerts in which we covered pop tunes. I'd really enjoyed the sound John Atkinson had gotten on his live Attention Screen CD, so I asked John to come out to Minneapolis and record us. I also thought it might be fun to make John abandon any remaining pretense of "minimally miked" recording and do it up with lots of mikes, like real rockers do. John will be the first to tell you that I'm a bad influence on him.
In order for us to sing with the bass…
The ceiling remains, but the floor has changed: Benz-Micro continues to offer a selection of rather expensive phono cartridges, including their well-established LP Ebony ($4700) and Ruby 3 ($3000) models. But in recent years, my attention has been drawn by the succession of budget Benzes: first, the Gliders ($795), then the ACEs ($550), and now the MC20E2-L ($199).
Actually, this particular Benz has been here before, but never with such a low output: The enduring MC20EII ($199) puts out a generous 2.5mV. But those who think of sub-millivolt cartridges as purer, quicker, and…