Stereophile – August 2019

stereophile.com n August2019 87

AESTHETIX AUDIO MIMAS

front end and an Audio-

Quest Niagara 5000 for the

power amps. I’m not the

only Stereophile reviewer

who finds that amplifiers

sound smoother when

plugged into a non–current-

limiting power conditioner

that’s designed to handle

heavy loads, with signifi-

cantly tighter bass—even

when, as in my case, that

wall houses a carefully

designed dedicated circuit

whose 8-gauge wiring is fed

by a relatively new

high-current power

transformer that serves only

five households. Jim White

seems of like mind when

he states, in the manual, “Although proprietary RFI

(radio-frequency interference) filtering is built into the

Mimas, in some situations an AC power-line filter may

provide additional sonic benefits.” My Niagara 5000 seemed

a good choice since, when AQ’s designer Garth Powell was

developing the Niagara, he tested it with an Aesthetix Atlas

power amp, among other equipment. I listened to the

Prix Monaco rack. To test
the Aesthetix’s integrated-
amplifier functions, I con-
nected the Rossini DAC’s
balanced analog outputs to
the Mimas’s analog Input 1,
turned the Rossini’s volume
control all the way up to
unity gain, then ran speaker
cables from the Mimas’s
easily tightened speaker
terminals to the Wilson
Alexia 2s.
Since the Mimas can also
function as only a preamp,
I also tried feeding signals
from the Mimas’s balanced
preamp outputs to my
reference Dan D’Agostino
Master Audio Systems Pro-
gression monoblocks to the Alexia 2s. Finally, I returned to
my reference configuration—Rossini DAC to Progressions to
Alexia 2s, volume controlled by Rossini—and listened again.
One big question concerned whether to plug the Mimas
into a power conditioner. Ever since we built my dedicated
listening room, I’ve regularly used two power conditioners:
currently a PS Audio DirectStream Power Plant 20 for the

B

efore measuring the Aes-

thetix Mimas with my Audio

Precision SYS2722 system

(see the January 2008 “As

We See It”^1 ), I installed its two Electro-

Harmonix 6922 tubes and left the

amplifier’s internal jumpers as set by

the factory. Before I test an amplifier,

I precondition it with both channels

driving a 1kHz tone at one-third power

into 8 ohms for an hour. The Mimas

turned itself off after 30 minutes,

however, its front panel displaying

the message “Temp HIGH RITE.”

The amplifier’s top panel was hot, at

126.6°F (52.6°C), the temperature of

the side panels was 110.4°F (43.6°C),

and that of the internal heatsinks was

163.5°F (73.1°C). The Mimas doesn’t

have quite enough heatsink capacity

for sustained high-power use.

After letting the Mimas cool down,

I continued the testing. Looking at

the line inputs—our review sample

didn’t include the optional phono and

digital input modules—the maximum

voltage gain at 1kHz from the speaker

terminals into 8 ohms, with the volume

control set to the maximum, measured

48.2dB for both balanced and unbal-

anced signals. The maximum gains at

the preamplifier and headphone jacks

were 29.3 and 27.1dB, respectively,

both higher than the norm. Both inputs

preserved absolute polarity from the

speaker and preamplifier outputs (ie,

were noninverting), meaning that the

XLR input jacks are wired with pin 2

hot. The headphone output inverted

polarity, however. The unbalanced in-

put impedance was close to specifica-

tion at a relatively high 19k ohms from

20Hz to 20kHz; the balanced input

impedance was twice that value, as

specified and expected.

The headphone output impedance

was an appropriately low 6 ohms at all

audio frequencies, while the preampli-

fier output impedance was 100 ohms

MEASUREMENTS

Fig.1 Aesthetix Mimas, frequency response at 2.83V

into: simulated loudspeaker load (gray), 8 ohms

(left channel blue, right red), 4 ohms (left cyan,

right magenta), 2 ohms (green) (1dB/vertical div.).

Fig.2 Aesthetix Mimas, small-signal 10kHz square-

wave into 8 ohms.

Fig.3 Aesthetix Mimas, spectrum of 1kHz sinewave,

DC–1kHz, at 1W into 8 ohms with volume control

at “88” (left channel blue, right red) and “68” (left

green, right gray) (linear frequency scale).

1 See http://www.stereophile.com/content/measure-

ments-maps-precision.

Hz Hz

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