Micromega AS-400 Integrated Amplifier Reviewed
By: Jim Swantko,
HTR Product Rating
- 4 Stars
- 4 Stars
- 4 Stars
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The AS-400 is essentially three high performance components in a single chassis: a preamplifier, a power amplifier and a state of the art digital-to-analog converter. The preamplifier incorporates several high-end design elements found in components costing significantly more. It is based around a very low noise design with its own dedicated power supply and R-Core transformer to eliminate cross coupling between the preamp and power amplifier sections. Ultra low noise regulators are also used to preserve maximum resolution of the delicate signals. Additionally, a digitally controlled resistor ladder is used for volume control, which is important for preserving phase equality between channels and imaging characteristics. This concept is very similar in design and function to my reference Mark Levinson No. 326S which also uses a digitally controlled ladder.
Operationally, the similarity continues in that the rate of change in volume is proportional to the speed in which the volume knob is turned. Turn the knob quickly and the volume steps are large; a slow turn results in smaller volume increments down to one-half decibel steps. Other notable features include preamp outputs for those who bypass the internal amplifier, nameable inputs, the ability to remove unused inputs from the input selector, and also a high quality MM phono section so turntable users can easily plug in.
The power amplifier section begins with a serious power supply consisting of a 1kVA toroidal transformer with fast recovery rectifiers and 40,000 micro Farads worth of smoothing capacitors in a dual-mono configuration. The amplifier circuit is a Class D design, which was chosen due to its compact size, high efficiency and sonic performance. The AS-400 generates 400 Watts of power into a four-Ohm load and we can only assume around 200 Watts at the industry standard measurement of eight-Ohms. Regardless, the AS-400 should have little problem driving most loudspeakers. The amplifier also features safeguards for under and over voltage as well as short circuit conditions and it also monitors for DC on the output to protect the loudspeakers from damage.
In my opinion, the most exciting aspect of the AS-400 is its integrated wireless DAC. The wireless AirStream module, based on the Apple Airport Express, has been completely redesigned since its original implementation in the Micromega WM-10 stand-alone wireless DAC. Utilizing the primary architecture of the Apple Airport express pays huge dividends in user friendliness and leverages the software might of Apple's iTunes software. The AS-400 is also able to take advantage of Apple's recently released AirPlay capability that allows for direct streaming of content from an iPhone or iPad - more on this later.
The new AirStream design utilizes three separate power supplies, one for the main module, one for the master clock circuitry and finally one for the D/A analog section. The master clock is also new and designed specifically to Micromega specifications, which provides astonishingly low jitter. Jitter is typically characterized as a smearing of the sonic image and Micromega went to great lengths in order to minimize it throughout the AS-400. The D/A converter is also completely new, based around a Cirrus Logic CS4351 chip that is capable of an impressive two Volt RMS output level. It's obvious that Micromega attacked every aspect of the digital circuitry and tweaked everything their engineers could think of.
The Micromega AS400 arrived double-boxed and well insulated with foam suspension packaging. Included with the unit was a somewhat flimsy multi-function remote control designed for use with other Micromega products. The remote was a bit of a tactile letdown as I expected something more substantial and to be honest, it felt downright cheap. To the remote's credit however, I must admit that I have never used a remote with better range and power than this one. Regardless of where I aimed the remote it operated the AS-400 without fail. In fact, at one point the AS-400 was turned around, facing the wall and it was still able to control it flawlessly. Oddly, I found that some of my DirecTV remote control signals also operated the AS-400. For example, pressing the volume up button on the remote would cause the AS-400 to power on. As I learned, there is no way around it due to a industry wide lack of codes, which results in overlap; thus this is a nuisance to anyone with DirecTV. I would assume this behavior is related to the sensitivity of the receiver that gave the AS-400s remote such amazing range, but at this price point it's something that needs a fix.
The operating manual was a brief two pages yet seemed to cover all the relevant points needed to get the AS400 up and running. One warning in the manual stated that nothing was to be placed on top of the unit and one should allow for at least thirty centimeters of ventilation above, which shouldn't be a problem considering the AS400 is about the size of a standard CD player, although significantly heavier than one. The specifications list the AS-400 at thirty-three pounds, but it felt much heavier.
My first impression of the Micromega case was that it was incredibly rigid and solid - think military grade. But Military grade finished with an eye towards beauty. Micromega uses a unique sandblast procedure that creates a surface that can't be characterized as smooth or rough, it's somewhere in the middle and has a very interesting feel. The top of the case was adorned with three rows of vents in the center, which not only break up the large surface but are necessary for venting the copious amounts of heat generated within the circuitry. My review unit was silver and pushed all the right visual buttons. The AS-400 is also offered in black, should it better suit your décor.
The eye is naturally drawn to the center of the unit where the large volume knob is surrounded with the only bit of bright work on the unit: a rectangular chrome surround printed with the model number, and the fact that it was proudly crafted in France. The chrome adds a bit of visual flair to an otherwise understated style. To the right of the volume is a large vacuum fluorescent display which provides source and volume information. Below the display is a row of buttons for input selection, monitor, mute, and headphone functions as well as a standby. The left side of the face has a convenient iPod input and headphone jack. Overall, the units styling is modern and elegant befitting a high-end product.
Moving to the rear of the unit, the space is dominated by a pair of large gold plated binding posts generously spaced for serious cables. They accepted my large Audioquest Colorado speaker cable spades with ease and felt as solid as any I have ever used. I would love to see other manufacturers follow Micromega's lead and stop with the cheap feeling plastic covered posts, which are unfortunately used everywhere with the exception of some mega-buck amplifiers. Moving right across the rear panel are placed several RCA connectors for preamp out, processor in and subwoofer out. The AS-400 provides a unity gain setting so its amplifiers can be used in conjunction with an A/V processor and also adds a subwoofer output for 2.1 configurations crossed at 400 Hz. Three sets of analog inputs round out the connection options. I was disappointed that no XLR balanced inputs were offered, as all I use are balanced cabling and assume many prospective buyers do too. The rear also houses the 802.11n antenna, which is a protruding semi-circular lump of plastic. Surprisingly, there was no digital input to let traditional sources take advantage of the fancy new DAC.
Integrating the unit into my system was simple once I dug out the RCA Audioquest cabling which I keep for occasions such as this. I connected my aging but still excellent sounding Esoteric DV-50 disc player, as well as my DirecTV HD-DVR and Sangean HDT-1X HD radio tuner.
I was very eager to take advantage of the AirPlay feature of the Micromega but was apprehensive of the complexity of making it all work. My research told me that it creates its own WHiFi (very cute, Micromega) network that will show up as a wireless network named "MUSIC". This network is used only for streaming music to the AS-400. In my laptop's Wi-Fi utility, I simply connected to the MUSIC network and opened iTunes. In iTunes you will find a new icon at the bottom right of the window in the shape of a small rectangle with a triangle at the bottom. Click the icon to choose the playback device, which in my case was either the laptop speakers or the AS400. Once the AS400 is selected you are free to stream anything from you iTunes library. It's very slick and works flawlessly. After a little encouragement from Mr. John Bevier of Audio Plus Services, the distributor of Micromega, I decided to push my luck and link my iPhone 3GS to the AS-400. I was running an older version of Apple's iPhone OS so I had to upgrade it in order to take advantage of the recently released AirStream feature. Once completed, I camped the iPhone onto the WHiFi network, selected it as my playback device and was streaming directly to the AS-400. I cannot overstate how cool this is, and how it encourages you to enjoy your music more often. When my wife wasn't looking, I put her iPhone on the network and told her to play a song. Her eyes lit up when she heard The Cure's "Pictures of you" (Fiction Records) from the Disintegration album start playing from the system. She spent the rest of the evening sampling her library and gushing over how good it all sounded. Maybe she'll finally get this whole audiophile thing after all. I was very pleased to see her having so much fun with the AS-400 and my all too manly hobby of audiophilia.Read about the performance of the Micromega AS-400 on Page 2.