sound by singer high end audio video tel: 212.924.8600 - fax: 212.366.6351
242 West 27th St, 2nd Floor
New York, NY 10001



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For 30 years, Sound By Singer has been the leading exponent of Krell sound in the world. The reasons for this are simple. First, Krell produces the most musical and technically advanced solid state hi fi components manufactured in the USA. Second, Krell, like Sound By Singer, is dedicated to propagating the best two channel and multi channel music sound possible.
That dedication has been renewed with a vengeance with the introduction of Krell’s I Bias series of preamplifiers, integrated amplifiers, power amplifiers, and digital sources. You could call it a Renaissance, but that doesn’t convey just how far Krell has once again advanced the art of music reproduction.



Connect Stream Player


The Krell Connect represents the ultimate in high-resolution audio streaming technology. From FLAC to WAV, MP3 and WMA, the Connect plays back up to 192kHz/24-bit audio plus Internet radio, all to Krell's highest fidelity standards.

The Wi-Fi equipped Connect is available in two forms: digital only, or with a built-in Digital-to-Analog Converter (DAC) module. The DAC-equipped Connect has a 32-bit ESS Sabre chipset with discrete, direct-coupled analog circuitry outputting via RCA or balanced audio outputs. The digital-only version has both coax and Toslink optical outputs.


Extensive audio libraries are easy to navigate via the Connect's built-in 3.5-inch QVGA LCD screen. Alternately, full-featured iOS and Android apps offer full control from anywhere in the home.


In addition to playback of FLAC and WAV files up to 192kHz/24-bit, the Connect also streams Ogg, WMA, and MP3. Unlike some music streamers, gapless playback is possible, allowing for no breaks between album tracks. Live concert albums, for example, can be played as a seamless, uninterrupted experience


Internet radio gets the same conversion as the high-resolution files (on DAC-equipped models), providing the best possible sound quality from on line streaming content.


Illusion Preamplifier

The Illusion preamplifier extends the Krell tradition of separating the power supply from the audio circuitry in our flagship preamplifiers. Sharing the new Class A iBias power amplifier aesthetic and featuring Krell CAST technology, the Illusion preamplifier is the ideal match for the new Solo 375 and Solo 575 power amplifiers.


The optional crossover functionality offers the ability to use a subwoofer/satellite speaker arrangement and still maintain the highest quality sonic performance. Previous to the Illusion preamplifier, this system configuration would require signals to pass through a subwoofer’s lower quality crossover circuitry. The Illusion preamplifier is the centerpiece of a world class audio system where space is at a premium.


Crossover Highlights
Owing to Krell’s work in the Modulari Duo Reference loudspeaker, the unique crossover feature is a highly sophisticated option. When the optional board is present, additional crossover menu items become available. Definable parameters include independently assignable crossover frequencies and filter types for the high and low pass sections. Choices include 40Hz, 55Hz, 75Hz, and 100Hz crossover points with 12dB, 24dB, and 48dB Butterworth or 24dB Linkwitz-Riley style filters. The high pass section of the crossover uses the full Illusion preamplifier circuitry for its output stage.



Circuitry Highlights
The Illusion preamplifier is a dual monaural circuit design with the left and right channels afforded their own power supply regulation and individual full chassis sized boards. All signal gain is realized in surface mount topology using proprietary multiple-output current mirrors with nearly 500 times the open loop linearity of other designs 1.5 MHz open loop bandwidth in a zero feedback, balanced, Krell Current Mode design terminating in Krell CAST. A complete Krell system (source, preamp, and amplifier) system, connected using CAST interconnects reduces the number of voltage gain stages to the minimum, one. The resulting noise floor approaches the theoretical limit of technology. Negative feedback is not used anywhere in the preamp, nor is it necessary. Open-loop distortion is typically less than 0.003%. The volume control is realized with a balanced resistor ladder — bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting.


Power Supply Highlights
The Illusion audio circuits receive power from a Krell Current Mode analog power supply housed in its own dedicated chassis. The power supply avoids the common integrated circuit topology used in many preamplifiers and instead mimics the design topology of Krell Evolution e Series amplifiers. The circuitry is completely discrete giving it the ability to respond quickly to current demands and also be unaffected by all but the most severe AC voltage power fluctuations. Oversized for a preamplifier, the power supply features a 290 VA transformer and 41,600µF of capacitance. Locating the power supply in its own chassis presents the ideal configuration for isolating stray electrical and magnetic interference from the critical preamplifier signal path. Capable of delivering current and voltage swing for any musical event, the Illusion power supply is gentle on AC requirements when not in use. A new eco-friendly design reduces standby power draw to 2W.





Illusion II Preamplifier

The Illusion II is the perfect centerpiece for a world class digital and analog audio system. Added to the normal selection of balanced and single- ended inputs are five digital inputs. The digital module features AES/EBU, coaxial, and optical digital inputs for use with streaming devices or other digital sources.


Circuitry Highlights
The Illusion II preamplifier is a dual monaural design with the left and right channels afforded their own power supply regulation and individual circuit boards. All signal gain is executed with surface mount technology using proprietary multiple-output current mirrors with nearly 500 times the open loop linearity of other designs. Featuring 700 kHz bandwidth in a zero feedback, balanced, Krell Current Mode design, the Illusion II shares the same design philosophy as its bigger brother, the flagship Illusion preamplifier. Negative feedback is not used anywhere in the preamp, nor is it necessary. Open-loop distortion is typically less than 0.003%. The volume control is realized with a balanced resistor ladder - bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting. The headphone circuitry is identical to the main circuitry, offering private listening with the same performance as speaker playback.


Digital Module Highlights
The digital module supports up to 24 bit/192kHz LPCM. All digital signals are fed to an ESS Sabre DAC and then sent to Krell’s Current Mode, discrete, balanced analog circuitry.


Power Supply Highlights
Oversized for a preamplifier, the power supply features a 95 VA transformer and 40,000 µF of capacitance giving it the ability to respond quickly to musical demands. The large power supply improves noise rejection and renders the Illusion II impervious to all but the most severe AC voltage power fluctuations. A new eco-friendly standby mode reduces power consumption to 2W.



All Krell amplifiers  are based on Their new Patent Pending Ibias Technologyso whether you are entering the Krell Universe with theeir entry level Duo 125 Stereo Amplifier or going right up into the amazing Solo 575 monoblocs you can rest assured you are going to be the recipient of that world famous Krell sound!

Krell Class A iBias Technology
Krell's history is rich with breakthrough Class A amplifiers that have helped build the Krell legacy of offering the best sounding amplifiers available. Audiophiles have always considered Class A technology to be the best sounding operating state for amplifiers. However, despite Class A's unrivaled sound quality, it has fallen out of fashion because of recent demands to reduce power consumption and heat in home electronics products. Krell engineering took this challenge and redefined the meaning of high performance power amplifier. Our goal - unmatched performance, elegant design, and a compelling array of features. The breakthrough - a patent pending circuit delivering Class A operation without the excessive heat and wasted energy of conventional designs, housed in a striking new form factor, with network connectivity for advanced access and monitoring. The sound is open and unconstrained, in a manner that rivals live performance and the true sound of voices and instruments. Music and dialogue are reproduced with a richness, detail, and startling dynamics that fill a room.


Plainly stated, Class A designs are the most musically accurate circuit topology available. Class A amplifiers do not suffer from the inherent distortions that all Class AB amplifiers experience. In a traditional Class A design, the output transistors conduct full current at all times regardless of the actual demand from the speakers. Often, only a fraction of this power is needed to reproduce an audio signal at normal listening levels. The rest of the power is dissipated through the amplifier’s heat sinks, producing large amounts of wasted heat. With Krell's iBias™ technology, bias is dynamically adjusted, so the output transistors receive exactly as much power - but only as much power - as they need.


Krell's iBias Class A technology allows our latest amplifiers to run in full Class A mode to full power while minimizing heat generation. Previous efforts at using a "tracking" bias, while effective, only measured the incoming signal and set bias levels from this information. Our new patent pending iBias technology significantly elevates the effectiveness of previous designs by calculating bias from the output stage. This seemingly small change in topology results in a dramatic improvement in sound quality, especially midrange richness and purity.


The core of the technology is an innovative, patent pending design for a dynamic intelligent bias circuit. Our iBias Class A circuit directly measures the output current of the amplifier and adjusts the bias to the optimum level. Because iBias Class A measures the output current, the real time demands of the specific speaker connected to the amp are directly incorporated into the circuit function. In addition, iBias Class A even reduces the bias when the signal is at very low levels, making its operation undetectable by ear and even by standard amplifier measurements.


In sliding bias schemes, the circuit merely estimates how much bias is needed based on the input signal and an "assumed speaker load." Compared with iBias Class A, these sliding bias technologies are much less effective - and much less accurate.


Power Supply Highlights
Power supply technology has always been an important contributor to the Krell sound. The power supplies of our Krell iBias Class A amplifiers have been optimized for use with the iBias circuit. Depending on the model, up to four toroidal transformers feed amplifier modules that include the audio circuitry, rectifier, and power supply filtering mounted to an individual heat sink. This design shortens the electrical path from the power supply to the output transistors, reducing the overall impedance and allowing the circuit to respond faster and control the speakers even better and more accurately.


Unlike traditional Class A amplifiers, iBias Class A amps have a compact design that allows rack-mounting, making them ideal for custom installation as well as traditional audiophile systems. This convenient form factor is made possible through thermostatically controlled ventilation fans. The fans used are specifically chosen for quiet operation, and operate at the speed required to maintain the ideal internal temperature. They run only during periods of peak energy demand - when the music is at its loudest - so they are inaudible in normal use.


Network Connectivity

The new amplifiers include RJ 45 Ethernet connectivity and an internal web page that is accessible from any smartphone, tablet, or laptop. Network connectivity brings convenience, monitoring, and reporting to end users. Amplifier configuration options include display brightness and timeout. For energy conservation, the amplifiers can be programmed to power off at a preset time of inactivity. Individual channels can be muted and firmware updates can be initiated from the web server.


Once the amplifier is connected to a network router with Internet access, the amplifier's advanced protection systems are now viewable on an Internet-connected device. Excessive current, output DC, fan speeds, short circuit, and overheating are all monitored in real time. If an issue occurs, the fault is displayed on the front panel and reported on the web server interface. Emails will automatically be sent to as many as three email addresses to notify the end user and/or the dealer of the condition.


Circuitry Highlights
The new iBias circuitry is built on a foundation of core Krell circuit technologies. All signal gain is realized in the current domain using proprietary multiple-output current mirrors with extraordinary open loop linearity. Each amplifier channel uses all discrete components. There are no generic integrated circuits or op amps used anywhere. Gain is distributed among several stages, allowing each to have a large linear operating area.


Audio signal voltages are converted to current at the amplifier input, and the audio signal remains in the current domain throughout the entire amplifier.


Current mirrors in the final gain stages use a new output power device that operates at a 73% higher voltage, delivers almost 10% more current, and offers 120 watts of additional power handling capability as compared to other devices.



With this combination, the iBias amplifiers may now deliver substantially more power while using a smaller footprint. Normally used in demanding, high-bandwidth video circuits, these transistors allow the design of gain stages with superb accuracy and very low distortion. The signal path is fully complementary and fully balanced from input to output. Independent complementary pre driver and driver stages for the positive and negative output transistors make the output stages extremely fast and linear. This unique circuit is impervious to low-impedance or reactive loads; it simply drives any loudspeaker with absolute confidence, achieving the very best possible sonic results.


Most amplifiers use coupling capacitors in the signal path to block DC and prevent damaging offset voltages from reaching your speakers. Krell amplifiers are fully direct-coupled, with no capacitors in the audio signal path. This design gives the Krell amplifiers lower internal impedance, which allows firmer, more precise control of your speakers. It also provides flatter, more extended low-frequency response, because coupling capacitors not only block DC but also affect the lowest bass frequencies. Krell employs expensive, non intrusive DC servos that remove DC without impacting the musical signal. Thus, the iBias Class A amplifiers deliver the full breadth of the music with detail, impact, and space intact.



Everything Audiophiles and Home Theater Fans Could Want in an Amplifier
Krell iBias Class A amplifiers are the first to deliver the rich musicality of Class A amplifiers, the uncompromised dynamics of classic Krell amplifiers, and the efficiency and low power consumption of Class G and H amplifiers.


Because the iBias circuit eliminates crossover distortion, the amplifier is able to resolve more of the detail and microdynamics in even the best analog recordings. Simply put, the music breathes. Whether an iBias amplifier is called on to reproduce the extreme dynamic range of high-resolution digital files, the minute intricacies of a 45-rpm, 180-gram vinyl record, or the complexity of today’s latest blockbuster action film, it does so without altering or abating the music in any way.


The iBias amplifiers' unprecedented ability to retrieve the subtlest details gives their sound an incredible dimensionality, with an ambient, broad and extraordinarily deep soundstage. As spacious as the sound is, though, the amplifiers are still able to produce pinpoint stereo imaging if the recording calls for it.


It's all the power and control for which Krell has always been famous, with a level of resolution and musicality in the midrange and treble that has simply never been heard before.


In short, the new patent pending iBias Class A Krell amplifers give today's audiophiles and home theater fans everything they could possibly want in an amplifier.




Krell’s new surround preamp/processor, the S-1000, combines robust, high-end audio performance with HDMI video switching in one easy to use, feature-rich package. A unique software-based eight-channel digital room equalizer maximizes system performance in any room.

Picture state-of-the-art digital audio chipsets, operating with upsampled 24-bit precision are utilized.

Digital audio formats include Dolby Digital Surround EX, Dolby Digital 5.1, DTS 6.1 ES, DTS 5.1, DTS NEO:6, and Dolby Pro Logic II, in addition to 9 proprietary Krell Music Surround modes.

Krell software provides digitally controlled bass management with user-selectable crossover points, optimizing the systems speaker/subwoofer interface.

Audio decoding is accomplished with 24-bit/192 kHz DACs, for the most accurate analog signal possible.

Krell Current Mode analog circuitry is utilized in the critical preamplifier section, and a fully balanced de-sign delivers the extremely wide bandwidth required for accurate audio reproduction.

An analog preamp mode bypasses all digital circuits, providing the most direct signal path for multi-channel and stereo recordings.

The S–1000 has 7 single-ended, 1 balanced, and 1 single-ended multi-channel analog audio inputs, as well as 6 coaxial and 2 optical digital inputs. Both single-ended and balanced analog audio outputs are utilized for all 7.1 channels.

A unique software-based eight-channel digital room equalizer maximizes system performance in any room. For each of four memory settings, the user can program filter type (high-pass, low-pass, notch, peaking, and high/low shelf), frequency, shape, and level for every channel. Each of the four memory settings is assignable to a device.

Video circuitry is fully discrete with a bandwidth of up to 350 MHz, ensuring the integrity of all progressive, high definition component, and HDMI signals.

Inputs and outputs for composite, S-Video, component, and HDMI are supported.

An on-screen display indicates status and facilitates system set-up.

FLASH memory enables easy software upgrades.

Evolution 707


The Krell Evolution 707 is an audio/video tour de force which delivers unparalleled music and cinema soundtrack reproduction through the use of a fully complement of advanced Krell technologies, including: Krell Current Mode, Evolution CAST, Class A, Evolution CAST and balanced outputs, user-configurable input assignment and system macros, main and remote zone control capability and broadcast-quality video circuitry.

Krell Evolution 707 features include:
8.4 channels of audio output features two center channel outputs and four subwoofer outputs for maximum flexibility in system design.

Two digital signal processors (DSPs), the Crystal CS49623 and CS49302 are employed to perform all surround mode processing.

Supports Dolby Digital Surround EX, Dolby Digital 5.1, DTS6.1 ES, DTS5.1, DTS NEO:6, Dolby Pro Logic II processing as well as Dolby TrueHD and DTS HD Master Audio lossless surround formats, plus nine proprietary Krell Music Surround modes.

Digital processing circuitry runs in double precision mode at a word length of 48-bits for the most precise division of frequencies and optimization of the system’s speaker/subwoofer combination.

12 output stages are fully balanced and feature Krell Current Mode topology with 1.5 MHz of bandwidth for accurate reproduction of today’s demanding movie soundtracks. Current audio signal transfer (CAST) outputs are supported for all 12 channels.

Evolution CAST, which stands for current audio signal transmission, is a proprietary method of sending the audio signal between components in the current domain, from a high impedance transmitter to a low impedance receiver. Krell components connected in Evolution CAST act together as an electrically unified whole, free from the deleterious effects normally imposed by the connecting cables.

Preamp mode bypasses all digital circuitry and routes the analog input, stereo or 7.1 multi-channel directly to the volume control for the purest path possible.

Separate power supplies for digital and analog circuit paths are linear design and feature custom made low-noise transformers and robust regulation.

All-discrete video circuitry bandwidth is greater than 350 MHz and provides pristine pass-through of all progressive and wideband high definition signals, including HDMI.

Faroudja DCDi Cinema (Directional Correlational Deinterlacing):
- A per-pixel video format converter – a unique algorithm identifies all the moving edges in a scene and adjusts the angle of interpolation at each pixel
- Eliminates staircasing or jagged edge artifacts
- Film mode detection features bad edit correction
- Emmy award winning

Faroudja Truelife Video Enhancer:
Identifies transitions considered to be the details in an image such as skin texture, freckles or hair for artifact free image enhancement.


The logical companion to the new S-1000 processor, the Krell S-1500 amplifier features legendary Krell amplifier performance in a multi-channel, upgradeable new design.

The S-1500 has a flexible design that delivers five, six, or seven channels of amplification. All three configurations include input and output connections for all seven channels. The S-1500/5 and S-1500/6 may be easily upgraded with additional channels, up to seven.

A 1,500 VA toroidal transformer is designed for massive current delivery while maintaining an ultra-low noise profile.

A robust, 80,000-microfarad array of quick-charging filter capacitance offers enormous energy storage that is available in an instant.

Surface Mount Technology is utilized in the amplifier channels to achieve the high circuit density required for wide bandwidth performance.

Krell Current Mode, fully balanced topologies, are utilized for all amplifier channels for the lowest noise and greatest detail retrieval.

Class-A circuitry is utilized in the input, pre-driver, and driver stages to provide the most accurate signal path.

Eight high-speed power devices per channel deliver 150 W into 8 Ohms and 300 W into 4 Ohms. The amplifier is stable at any load impedance.


All channels support balanced inputs and outputs. High quality, 5-way binding posts allow speaker connections via bare wires, spade lugs, or banana plugs.