The best possible fidelity.

Achieving a perfect balance between the two halves of an audio signal is possible only when the incoming signal is itself perfectly balanced. This is why the Inspiration STEREO 1.0 uses the same Line Stage Gain Module circuit found in all Constellation Audio products. The Line Stage Gain Module’s servo circuits assure that both halves of an incoming signal are perfectly balanced, no matter what the source.But if the source is a Constellation Audio preamp — which of course has its own Line Stage Gain Module — then so much the better. Because you can then use the Constellation Direct balanced input, which bypasses the Inspiration STEREO 1.0’s input stage for the best possible fidelity.

A cool, reliable operation.

A custom-wound toroidal transformer, feeding a total of 24 capacitors yielding a combined 240,000 microfarads of storage, assures that the Inspiration STEREO 1.0’s output stages always receive the clean, ample voltage and current needed to achieve maximum musicality and sonic transparency. Massive heat sinks, ventilated through hundreds of ventilation ports in Constellation Audio’s trademark machined-aluminum side panels, assure cool, reliable operation

200 watts per channel into 8 ohms

With power output conservatively rated at 0.2% total harmonic distortion plus noise, doubling to 400 watts into 4 ohms, the Inspiration STEREO 1.0 has enough power to drive practically any speaker to maximum volume without audible distortion.

Balanced bridged design from Hercules and Centaur

The Inspiration STEREO 1.0 uses a modular, fully balanced design with only N-type output transistors, instead of half N-type and half P-type as found in almost all other solid-state amplifiers. Thus, the positive and negative halves of the audio signal are maintained in ideal balance and the subtlest of musical details are preserved.

Line Stage Gain Module

Incoming signals are treated to our Line Stage Gain Module circuitry, which uses servo circuits to achieve essentially perfect balance between the positive and negative haves of the audio signal. If a Constellation Audio preamplifier is used, this input stage may be bypassed through use of the Inspiration STEREO 1.0’s Constellation Direct balanced input.

Fully discrete circuitry

As with our other amplifiers, we use only discrete components in the Inspiration STEREO 1.0’s audio circuits.

Ultra-smooth, high-current power supply

A large, custom-wound toroidal transformer feeds a bank of 24 capacitors rated at 10,000 microfarads each, assuring that the Inspiration STEREO 1.0’s output stages have more than enough current to deliver their rated power with ease — and enough dynamic output to achieve concert-sound levels, if your speakers are up to it.

No output filters required

The inherent stability of our Balanced Bridged design allows us to dispense with the Zobel output filter network many amplifiers require to maintain reliable operation.

Shortest possible signal path

by placing the transformer at the front of the Inspiration STEREO 1.0 and moving the output stages to the rear, we ensure the shortest possible signal path and very low output impedance.

Shielded enclosure for power supply

To minimize interaction of the transformer’s electromagnetic fields with the audio circuits, we place the transformer in its own enclosure and shield it with thick aluminum plates. A special shielded channel carries the AC voltage from the power input to the power supply enclosure


inputs:                                                                      1 Constellation Direct XLR, 1 standard balanced XLR, 1 unbalanced RCA
Outputs:                                                                   metal binding posts
Power output:                                                          200 watts, 8Ω (1 kHz @ 1% THD+N)       400 watts, 4Ω (1 kHz @ 1% THD+N)
Gain:                                                                       14dB Constellation Direct, 26 dB Balanced & RCA
Output noise:                                                          <70 µV, 500 kHz BW, -116 dB @ 250 watts
Damping factor (8Ω load):                                       80
THD+N:                                                                  <0.05%, 1 kHz @ up to 90% of rated power
Frequency response:                                              10 Hz to 80 kHz, +0/-0.5 dB
Signal-to-noise ratio:                                              >-95 dB, A-weighted
Input impedance (balanced):                                  20 KΩ Constellation Direct, 20 KΩ XLR
Input impedance (unbalanced):                              10 KΩ RCA
Output impedance:                                                 0.1Ω
Weight                                                                    80 lbs / 36.3 kg


get more reader letters complaining about the prices of some of the products we review than on any other topic. Six-figure amplifiers are bound to offend many sensibilities. But I’m about to demonstrate how the development of those cost-no-object components can benefit music lovers of more modest means.

Exhibit A is the new and relatively affordable Inspiration Series electronics from Constellation Audio. You may recall that back in 2008 this newly formed company launched a no-holds-barred assault on the state of the art in solid-state amplification by assembling a team of the world’s greatest electronics designers—a “constellation” of audio stars, if you will, that included Peter Madnick, Bascom King, the late James Bongiorno, John Curl, and Demian Martin. They were given a mandate to do the best work of their illustrious careers without regard for time or cost. No idea, design, or implementation, however expensive or exotic, was off the table.

The result of that effort was the $65,000 Altair preamplifier and $140,000-per-pair Hercules monoblock power amplifiers. The design and execution of these electronics were beyond heroic. To give you but a single example, the Altair’s volume control attenuated the signal by inserting in the signal path a single resistor—without any mechanical connections or relays. This feat was achieved with an elaborate circuit that involved 48 pairs of light-dependent resistors, corresponding LEDs, and a DAC, all under software control. (I could have cited any number of additional cutting-edge circuits developed for the Reference Series—this was clearly a landmark effort.)

So how did the Reference Series sound? In my review in Issue 215, I concluded, “Constellation has established a benchmark against which all other linestages and power amplifiers can be compared.

Looking back now, I can see that the development of the Altair and Hercules wasn’t purely intended to sell $65,000 preamps and $140,000 power amps. Rather, Constellation wanted to create platforms for discovering optimum circuit topologies and to establish a performance benchmark. Once created, the reference-level products would inform more affordable implementations that would be accessible to a wider audience. In my view, the ultimate goal of the Altair and Hercules design project was the Inspiration Series reviewed here.

It sounds simple in theory, but creating a successful trickle-down model is easier said than done. It requires that the initial development effort produce components that are truly world-class—which is far from a given. Then the reference-level products must sell in sufficient numbers to sustain the company. Finally, the firm’s founders must possess long-term vision, not to mention adequate capitalization. But when it works, trickle-down engineering can bring to mid-priced products the essential DNA of cost-no-object components.

The three products in the Inspiration Series are the Preamp 1.0 linestage ($9000), Stereo 1.0 stereo power amplifier (200Wpc, $10,000), and Mono 1.0 monoblock power amplifiers (400W, $20,000 per pair). Although not budget-priced by any stretch, Constellation products at these prices represent quite a breakthrough. This is particularly true when you consider that the Inspiration Series uses exactly the same audio circuits designed for the Altair and Hercules. The $9000 Preamp 1.0’s schematic (and even the audio circuit-board layout) is identical to that of the $65,000 Altair (and to the Virgo). The Stereo 1.0 and Mono 1.0 amplifiers employ the identical topology as the Hercules, along with many of the same components, including the transistors in the input, driver, and output stages. The cost savings are realized with simpler implementations of the same fundamental platforms. The circuit design isn’t what’s expensive in an audio component (after the R&D has been amortized), so why not use the best topology at every price level? I don’t think I’ve encountered an example of trickle-down engineering in which the progeny hews as closely to the parent as it does here (see sidebar for details).

Even the Inspiration’s styling, build, and visual aesthetic come close to those of the Performance and Reference Series. I had the $24,000 Virgo II and $9000 Preamp 1.0 in my rack at the same time, and sometimes had to do a double-take to know which was which. A closer look, however, reveals some clever techniques for saving money on the casework without diluting the aesthetic.                                 READ MORE