Dan D’Agostino Momentum Z

 

Taking the Lead

The new Momentum Z Monaural Amplifier marks the next stage in Dan D’Agostino Master Audio Systems relentless pursuit of musical perfection.

Introduced in celebration of the company’s fifteenth anniversary, it builds upon the core technologies that have defined our amplifiers—advanced circuit design, precision-machined enclosures, and extraordinary power delivery. The Momentum Z takes performance to an entirely new level of refinement and control.

Born from the same design philosophy that established the original Momentum series as a benchmark in high-end amplification, the Momentum Z generation advances every facet of the platform. Its unique power supply technology, the Kinetic Drive Regulator, keeps the amplifier immune to AC mains irregularities and the speaker interaction issues that commonly degrade the performance of conventional amplifier designs.

In addition to this proprietary innovation, every element of the Momentum Z has been reimagined, including the input stage topology, output stage circuitry, and an advanced software-based control system that optimizes the operation of every circuit group. Integrated within a newly refined thermal architecture, the Momentum Z delivers effortless dynamics, exceptional transparency, and a lifelike sense of musical scale.

Input Stage Highlights

The Momentum Z is the first D’Agostino amplifier to use a Junction Field-Effect Transistor (JFET) based input stage. At the very front end of an amplifier, where the delicate musical signal first enters the circuit, the choice of device is critical. JFETs excel in this role, offering ultra-high input impedance and exceptionally low noise, which together preserve every nuance of

the source signal. From a technical standpoint, JFETs operate in a manner that provides a smooth, linear transfer characteristic with natural load handling. This design minimizes distortion and ensures that micro-level musical details are passed into the amplification stages intact, without being masked or colored. The benefits are immediately clear: a quieter background that reveals subtle spatial cues, a more natural midrange presence that brings vocals and acoustic instruments to life, and a sense of openness that enhances the soundstage. By using JFETs in the input stage, the amplifier achieves a rare balance of technical precision and musical warmth, allowing recordings to be experienced with both accuracy and emotional impact.

Internet Connectivity

With an integrated RJ45 Ethernet connection, the Momentum Z provides a glimpse into the performance and service parameters the software-based control system is optimizing. Through any web browser, users can view amplifier performance data including operating voltages, temperature, bias, DC offset, 12V trigger status, and more—all continuously monitored and displayed on connected devices via their home network. The same dashboard also provides control over front panel display settings for a personalized user experience.

Design

A defining hallmark of Dan D’Agostino Master Audio Momentum amplifiers is the distinctive use of solid copper heat sinks, a choice driven equally by engineering performance and visual impact. With nearly twice the thermal conductivity of aluminum, copper draws heat away from the output devices more quickly and uniformly. Immediately striking is the new, advanced 5-axis machined copper heat sink design, each formed from a single 42 lb (19 kg) slab of copper billet. The highly efficient elliptical geometry significantly enhances cooling performance, ensuring that Momentum Z operates safely and reliably even at full power. This exceptional thermal efficiency not only improves long-term reliability and longevity, but also maintains optimal operating conditions for the amplifier’s critical circuitry, preserving sonic stability under the most demanding loads.

The Momentum Z features a Dual Domain Meter Display designed to echo the elegance of the Swiss watch, inspired analog meters found throughout the D’Agostino product line. The first domain is digital: in place of a passive meter face, Momentum Z employs a 3.5-inch high-resolution LCD that serves as both a power meter and a message display. The second domain is analog, where – true to D’Agostino tradition, power is indicated by the iconic meter wand, a defining visual and functional element of D’Agostino power amplifiers.

Specifications

Power Output

500 watts @ 8 Ω / 1,000 watts @ 4 Ω / 2,000 watts @ 2 Ω

Frequency Response

1 Hz to 200 kHz, -1 dB / 20 Hz to 20 kHz, +0.1 dB

Signal-to-Noise Ratio

>75 dB, A-weighted / >115 dB, unweighted

Gain

27dB

Distortion

0.1% @ 1 kHz, 250 W per channel @ 8Ω

Input Impedance

1 M Ω (Standard Input setting) 300 Ω (Z input setting)

 Output Impedance

<0.05 Ω, 20 Hz to 20 kHz

Output Voltage

190 V peak-to-peak

Output Current

60A peak-to-peak

Power Consumption

Standby 17 W / Idle 35 W / Maximum 2,000 W

Inputs

1 balanced XLR

Outputs

1 pair binding posts 

Dimensions (WHD)

13.5 x 5 x 20.5 in / 32 x 13 x 54 cm

Weight

100 lb / 45 kg

Finish

Silver or black

LampizatOr Aphrodite

 

Zellaton Statement Ultra

 

Franco Serblin Accordo Unica

 

Zellaton Statement Ultra

 

Sigma Acoustics Orchestra 2.9 Limited Edition

 

Stellavox IDEM

 

Stellavox is a prestigious company that carries a long history in Switzerland, which was founded by the exceptional Georges Quellet who is 96 years old now. In fact, Rolland Schellin from Berlin wrote a book about its history 25 years ago. 

 

Stephan Schertler, the current head of research and development will lead Stellavox to the next stage.  He and the Stellavox team will only develop innovative electronics.

In 2019, he was given the opportunity to develop a studio console and other pro audio devices for the newly founded Stellavox company in Mendrisio, Switzerland, leveraging on his immense researches on zero-feedback technology in the last 25 years.

He was graduated as an engineer in 1983 and attended the Jazz Conservatory for several years.  At 26, he decided to devote himself entirely to music and toured as a double bassist all over Europe as a key member of Franco d’Andrea Trio, playing mostly with Italian and American Jazz musicians.

Due to the absence of supreme quality bass microphones, he developed his own and subsequently got a patent on the invention of a new transducer principle.  Then he founded the Schertler company and began a life long journey on audio electronics development. 

Since 1998 he had been working on the realization of new circuit principles for all audio functions without negative feedback, seeking for the sound of utopia in his mind. 

 

He is the mastermind behind the IDEM mono amplifier, an original work of his own without any commercial orientation that spans a few decades.  They are physically small but immensely powerful with supreme transient response. They can challenge any big boy with ease. It game-changes the definition of transparency in an uncharted territory.  It is not the typical “Swiss” sound like Dartzeel and others in similar camp.

icOn 5 Dual

 

The Dual version is a true high-end Jolly Joker autoformer-based line control unit. It features both RCA and XLR input and output sockets, making it an ideal match for most audiophiles with both analogue (like vinyl) and digital sources (DAC, CD player). It offers remarkably precise volume adjustment capabilities, spanning 136 steps within an 83 dB range. The Dual has a fully passive analogue signal path between the RCA sockets and active, electronically balanced circuits between the XLR sockets.

The inclusion of the optional input buffer, coupled with the lower inductance autoformers, along with the finely adjustable volume control in increments of 0.5 dB and the tilt control, results in an astonishingly lifelike auditory experience.

Features:

Unprecedented 136 steps over an 83 dB attenuation range

0.5 dB steps from +3 dB to -47 dB with the buffer and 1 dB from -48 dB to -80 dB or without the buffer

Unbalanced operation between the RCA sockets, electronically balanced between the XLR sockets

1 RCA + 1 XLR input & 1 RCA + 1 XLR output

Improved linearity and transparency due to the new, lower inductance autoformer

The silver winded autoformers are our own production with 80% Ni core

Optional input buffer for the total source compatibility

FET switches for the autoformer taps' selection

Max. input level: 8V RMS (22.6 Vpp)

Balance, mute and standby mode

Optional tilt control (defeat-able) with 8x0.5 dB steps for fine-tuning the record and room acoustic imbalances

Remote-controlled output selector

Large (0.8") 3-digit white or orange display with 2 brightness and night mode

Apple remote-compatible IR remote controller

Optical encoder and touch button for the manual operations

90mm high BLACK enclosure (W 124mm x L 260mm)

"Power" users can increase the number of inputs anytime with the icOn I/O Expander (+2 RCA & 2 XLR sockets)

ALIENO Phono Extremo

 

Specs:

Three Rca inputs, selectable from the front panel;   output on Rca and XLR connectors.

Three equalizations available, selectable from the front panel: Decca, R.I.A.A., Columbia

Stereo-Mono switch on the front panel.

Gain: 66 – 60 – 54 dB selectable from the rear panel.

Cartridge load: via Rca plugs of the following values: 100, 220, 330, 470, 750, 1000 Ohm.

Signal to noise ratio: > 80dB @ 1mV input.

Total harmonic distortion: < 0,05 %.

Equalizations frequency response:  +/- 0.1dB.

Headroom (max. output level with zero distortion): over 25 Vrms.

Output impedance: 250 Ohm, low value ideal also for driving line preamp or integrated amplifiers with critical impedances starting from 2500 Ohm.

Tubes: 12AY7 and ECC83, low-noise amplifier cascode stage;

E8CC driver stage of equalization networks;

ECC82 further amplifier stage;

E88CC buffer stage to drive the output.

Power supply unit with Virtual Battery Powered technology: 240-115 V~ ±10% / 50-60 Hz

Main fuse: T1Ampere (T2Ampere for 115 V).

Power consumption: 100VA approx.

Dimensions:

Amplifier section: L x P x H, cm/inch. 45/17,7” x 41/16,1” x 22/8,6, weight 15 kg – 33 lb.

Power supply section: L x P x H, cm/inch. 33/13” x 32/12,6” x 10/4”, weight 9 kg – 19,8 lb.

ALIENO Phono Preamplifier

 

Specs:

Two Rca inputs switchable from the rear panel; Rca and XLR output.

Gain: 66 – 60 – 54 dB, selectable by internal dip-switches.

Cartridge load: via Rca blind plugs: 100, 220, 330, 470, 750, 1000 Ohm.

Weighted signal/noise ratio: > 80dB @ 1mV input.

Harmonic distortion: < 0.05 %.

RIAA equalization frequency response: +/- 0.1dB.

Headroom (maximum undistorted output level) over 25 Vrms.

Output impedance: 250 Ohm, low value ideal for driving even line preamplifiers or integrated amplifiers with critical impedances starting from 2500 Ohm.

Tubes: 12AY7 and ECC83, low noise cascode amplification stage;

E88CC equalization network driving stage;

ECC82 additional amplification stage;

E88CC buffer stage for output driving.

Power supply unit with Virtual Battery Powered technology: 240-115 V~ ±10% / 50-60 Hz

Main fuse: T1 Ampere (T2 Ampere for 115 V).

Power consumption: approximately 80VA.

Amplifier section dimensions: L x D x H, cm/inch. 45/17,7” x 41/16,1” x 18/7”, weight 12 kg – 26,4 lb.

Power supply section: L x P x H, cm/inch. 33/13” x 32/12,6” x 10/4”, weight 9 kg – 19,8 lb.

ALIENO Amplifier 150-120 LTD

 

Same characteristics of ALIENO 100, but ALIENO 150-120 can use the two most famous direct heating triode tubes at the user’s choice: the 300B to deliver 150 Watts per channel, or the 2A3 to deliver 120 Watts per channel.

In addition to the power supplied, this amplifier also modifies its sonic characteristics respecting the type of tube used.

A double display on the front panel shows the type of tube installed, to confirm to the user that ALIENO has simply and automatically adapted all the parameters for the chosen tubes, avoiding the need for external modifications or the use of any tools.

Optimal load impedance 2 – 8 Ohm. XLR and RCA input connectors.

Like all ALIENO amplifiers, the 150-120 also uses the proprietary LTD (Loudspeaker Tube Direct) technology, in pure Class A, OTL-OCL and totally absent negative feedback.

YS Sound YSS-988

 

Rotaxis Core64

 

Introducing the Rotaxis DAC – A New Era in Digital-to-Analog Conversion

After years of listening, testing, and rethinking what digital audio should be, I’m proud to introduce something that isn’t just another DAC—it’s a redefinition of what digital audio can sound like when built without compromise. This is the Rotaxis DAC.

It’s not just designed for measurements. It’s not another op-amp box wrapped in marketing.

Rotaxis is a ground-up, time-domain focused, passive resistor ladder DAC built for one purpose:

To render music in time, not in code.

What Makes It Different?

Most DACs today rely on high-speed digital correction tricks like delta-sigma modulation, noise shaping, or digital filters that manipulate the signal to achieve good measurements. Rotaxis does none of that.

Instead, it’s built around a unique architecture:

1. PulseAxis Ladder Design

At the core is a true resistor ladder array using 24 bits of resolution. Each bit is represented by a series of precision-matched resistors ( typically 64 for each exponentially weighted bit) arranged in a circular configuration we call the PulseAxis Array. These aren’t just resistors lined up on a board—they’re strategically interwoven in rotational rings to reduce electromagnetic interference, thermal drift, and crosstalk.

Each bit doesn’t fire statically. It fires with clock-controlled precision at 11.2mhz base rate with sub clocking nearing 100mhz— firing each ladder in timed quarter clock time quadrants grouped by current weighting (MSB’s first)—to allow each resistor to settle before the next one activates. This gives a completely clean handoff across voltage levels, with no overlap, no popping, and no zero-crossing errors.  The averaging effect per bit outperforms the best laser trimmed monolithic designs and even approaches metrology levels, and is SCALABLE for everything from a future accessible entry level product with only 32 level unary rings per exponential bit, all the way to 4 rings of 64 in each singular bit!!!  With physically interwoven rings on the PCB that rotate in opposite polarities to eliminate EMI RF.  A self-cancelling noise system.

2. Thermaphase Averaging

Instead of applying digital noise shaping, the Rotaxis uses a proprietary analog system called Thermaphase, which is deterministic rotation per bit that ensures perfect thermal symmetry as well as injecting inaudible ultrasonic dither into the 8 LSB’s where real music lives.  Rotaxis behaves the way true analog signals behave in the real world.

This allows for incredibly smooth low-level performance—something most DACs struggle with. In Rotaxis, the bottom bits—the bits where the soul of music lives—are given the most care: the best resistors, the most error-averaging, and the cleanest timing.

Idle tones are a thing of the past.  The 64 bit rings prevent audible pattens, and send whatever is left well into the ultrasonics which is filtered by a 4 pole RC filter into oblivion.

3. GlitchLock Timing

Instead of relying on one massive clocked update cycle, Rotaxis staggers its activity with a timing system called GlitchLock, breaking the update cycle into quarter-clock pulses within the DAC, and eighth-clock offsets between the two polarity ladders. This ensures that current never surges or overlaps across bit boundaries, minimizing distortion and noise.

The result is ultra-low distortion—without any digital filtering or shaping.

4. Transformer-Coupled Class A Output

We don’t use op-amps. The Rotaxis output stage is fully Class A, discrete, and transformer-coupled using premium Lundahl components. This preserves phase, eliminates ground loops, and gives the kind of dynamic immediacy you’d expect from the best analog gear.

5. Modular and Upgradeable

The Core64 model launches with:

 • USB, SPDIF, and I²S inputs

 • Galvanically isolated power (external PSU only)

 • No touchscreens, no noise—just a small LED volume and sample rate indicator

In the future, an external streaming and control box will connect via I²S over HDMI, letting Core64 owners expand their system without changing the DAC core.

Measured Performance?

THD+N better than –124 dB, real-world.

No noise shaping. No feedback. No tricks.

Just physics, design, and care.

YS Sound YSS-998s