Further Thoughts: Aesthetix Mimas Integrated Amplifier

The Aesthetix Mimas is one of the finest integrated amps on the market today. It’s an absurdly good value, to boot, and one of my recent Golden Ear Award recipients. At the time of the original review’s publication, however, the development of an optional, inboard, modular phono card was still ongoing. Knowing I am an avid analog guy, Aesthetix’s Jim White pledged that as soon as the $1250 phono card was in production he’d slip it into the assigned open bay on the back panel of my Mimas review sample, and I’d get a listen. True to his word, the installation was completed a few months ago. 

Analog LP playback has been a specialty of Aesthetix from its earliest days. The company knows the territory like few others, as owners of its widely respected dual-chassis Io tube phonostage will attest. By contrast, inboard phonostages have a checkered history. Typically built to a modest price point, they rarely enjoyed or deserved the kind of deference vinyl enthusiasts lavished on stand-alone models. Further, as analog faded to a “legacy” format with the rise of digital audio, most inboard phonostages—often noisy and hum-prone—got bundled into budget AVRs or amps as promotional afterthoughts. The resurgence of analog playback changed that equation, and performance expectations have risen commensurately.

Remarkably, given the small proportions of this phono card, its feature-set still approximates many formidable stand-alone phono preamps. It sports both mm and mc capability with adjustable gain and loading. In addition, a dual set of individually adjustable inputs gives die-hard analog enthusiasts the option of preserving gain/load settings for two cartridges or, as the turntable budget allows, of supporting dual tonearms. Its fully discrete, FET-based, high-gain differential circuit utilizes Wima film capacitors for RIAA compensation. 

Installation of the phono card (a dealer is recommended) instantly activates phono/cartridge configuration software that’s driven from the Mimas’ front panel or remote control. Setup is as easy as selecting the “TT” input and following the menu prompts—no dealing with those annoying back-panel DIP switches. For evaluation, my cartridge selection included three designs of varying output voltage—a Clearaudio Charisma V2 (mm, 3.6mV), a Sumiko Palo Santos Celebration (mc, 0.5mV), and an over-performer of a budget cartridge, the new Grado Opus3 (mi, 1mV). My longstanding LP rig is an SME V tonearm mounted on a Sota Cosmos Eclipse turntable.

The truth is that phono- stages—be they onboard or outboard—live or die based on delivering the lowest possible noise. The noise issue is particularly acute with lower-output cartridges, which require greater phonostage gain to boost their miniscule voltages. The challenge for phonostage designers is that the higher the gain, the greater the potential for added background hum and hash. There are no free rides. 

That said, for current Mimas owners who’ve been pining for the full-on, ultra-low-noise vinyl experience, the wait is over. Sonically, the Mimas phonostage’s character dovetailed with the sonic signature of the Mimas amp, with gentle hints of midrange warmth and rosy, extended sweetness in the treble. The waft of harmonic air and treble extension that vinyl aficionados crave was realized in abundance, as was a sense of the tactile and the intimate—peculiarities of LP playback—that seem to enhance female vocalists, such as the timeless Jennifer Warnes singing Eddie Vedder’s “Just Breathe” [Another Time, Another Place, BMG]. Even at the highest gain setting with the lowest-output mc in my collections (the Palo Santos), the Mimas phonostage was astonishingly quiet—comparable to outboard standouts like the Pass Labs XP-17 and Parasound JC 3+ phonostages that I had on hand.

The Mimas’ rendering of soundstage dimensionality and immersion were exactly what I’ve come to expect from excellent analog. This was nothing like the collapsing constrictive soundstages that characterized inboard phonostages from the past. Images were reproduced with substance and transparency. Clusters of players—choirs, chamber groups, or jazz quartets, for example—were conveyed with superior separation and were also integrated easily within the auditorium environment. Orchestral layering and focus extended to near the back of the hall. 

Beyond the pastoral calm and quiet this phonostage conveyed, the Mimas also had another, more assertive side to its personality. And, frankly, during the “Olympic Fanfare” from Winds of War and Peace [Wilson Audio], I was a little stunned by the resolution, fearsome bass reproduction, and transient fireworks springing from this classic piece of vinyl. Set against its noise- and grain-free silences was this phonostage’s most noteworthy feature—the ability to reproduce and resolve the widest dynamic contrasts, from the softest keyboard pianissimo to the most explosive orchestral tuttis. The track that comes to mind is the cratering darkness of Holst’s “Mars, The Bringer of War” [The Planets, LSO, Previn, EMI]. Through the Mimas phonostage, the full weight of brass and winds, screaming strings, and relentless percussion was brought to bear in the nightmarish soundscape of horror, loss, confusion, and grinding despair of armed conflict. Or, take Norah Jones’ quirky track “Sinkin’ Soon” [Not Too Late, Blue Note], with its pots-and-pans percussion, its burbling trombone accents, and gossamer backing vocals—low-level voicings that swing in and out at unpredictable moments and occupy oddball stage positions. Through the Mimas, the energy jumped from this playfully idiosyncratic track at all levels. While I haven’t heard every phonostage out there, it’s hard to believe that this unit left much, if any, resolution on the table.

Is the Mimas phonostage the end of the line in resolving power and musicality? A fair question. The answer is, first, no competitor I know of will embarrass it, and second, you’ll have to dig a lot deeper into the mid-four-figure phono preamp range to equal it. The Aesthetix modular phono card completes an already premium package in the integrated amplifier segment. I originally dubbed Mimas “the very definition of what I am seeking today in an integrated amplifier,” but now I’m happy to amend that characterization. Now, it’s also among the most versatile. 

AESTHETIX AUDIO CORPORATION
5220 Gabbert Road, Suite A
Moorpark, CA 93021
(805) 529-9901

Base Price: Mimas $7000 (add $1250 phono option)

Jim White on the Mimas Phonostage

What are the chief challenges and pitfalls of building a phono- stage into an integrated amplifier?

There are two major challenges of building a phonostage into an integrated amplifier: power supplies and magnetic fields. Power supplies become an issue because, typically, you are drawing current from supplies that perform other key functions, such as powering the main gain stage or, in extreme cases, the high-current output supplies. Mimas was designed from the ground up to have a special power supply, with its own transformer winding, that would be used for optional cards such as the phono, and be minimally used for other functions. It is a very stiff, high-current power supply. Further, we double-regulate that power supply on the phono card itself, to fully isolate it from any noise or fluctuations.

Magnetic fields are a problem because of the large power transformers that are required for power amplifiers. These fields can leak into the phono section and cause big problems. For a phono section only intended for moving-magnet cartridges (with about 40–60dB of gain), it is not a big problem. But for a phono section intended for low- and medium-output moving-coil cartridges (with 60–75dB of gain), it is a much bigger issue. We wanted this module to be something very special, so we went to great lengths to be able to easily handle medium- and low-output mc cartridges as well as mm’s. The input section uses a six-layer board, using the outer four layers almost exclusively for shielding. All of the circuitry is fully discrete, using Toshiba FETs, which we hand-match. This matching allows for greatest CMRR (common-mode rejection ratio, a measure of a circuit’s ability to reject outside sources of hum and noise). The fully discrete design allows us to optimize the PCB layout, among many other advantages. Further, the entire input section is encased in mu-metal to shield it from stray fields. 

What are the limitations of an inboard phonostage?

Typically, you do not find a truly high-performance phono section in an integrated amplifier, especially a fully discrete one capable of handling low-output mc’s. They are mostly limited to lower gains (for the above-mentioned reasons) and do not offer the flexibility to interface with a wide variety of cartridges. They are often meant to provide basic phono amplification, but not performance that is competitive with stand-alone phonostages. From the outset, our design team planned for Mimas to incorporate a state-of-the-art phonostage, so many of the pitfalls were avoided upfront. Nevertheless, it proved to be massively challenging, requiring over two years of work and no fewer than five full prototypes. 

How does modular design make for a better phono card?

The modular design allowed us the opportunity to fully focus on the phono module as a product of its own. We can then optimize every aspect of performance and functionality, without the time and financial constraints that would be imposed by a non-modular approach. Most importantly, a modular approach allows for future upgrades and new features to be implemented without the need for an overall product redesign.