The A&ultima SP4000 by Astell&Kern (A&K) represents the latest flagship digital audio player, emerging from three years of dedicated research and innovation following the SP3000. As a part of the esteemed A&ultima series, the SP4000 surpasses the limitations established by its predecessor. It features an advanced Octa audio circuit architecture that captures the essence of audio engineering, providing an exceptional sound experience that is both refined and powerful, approaching perfection. The new circuit design integrates a single AK4191 digital processor with a single AK4499EX analog DAC, ensuring precise routing of digital signals to the DAC chip while minimizing noise interference. This advancement enhances signal separation and processing capabilities. In contrast, the SP3000 utilized a single AK4191 processor with two AK4499EX DACs in a 1:2 configuration. The SP4000’s innovative 1:1 signal processing architecture successfully achieves a true Quad DAC, overcoming previous challenges related to noise and other technical limitations.
Most digital players process both digital and analog signals together in the DAC. However, the SP4000 reduces noise from the digital input signal by using the AK4191EQ, a separate digital delta-sigma modulator, and then the AK4499EX DAC to process the analog signals separately. This unique design, where digital and analog signal processing are physically separated, makes it possible to experience incredible sound levels never heard before, A&K explains.
The SP4000 features two paralleled OP AMPs for richer, more detailed sound. In a parallel op-amp configuration, the range is expanded horizontally without increasing noise or decreasing the S/N ratio. This results in a wider dynamic range and enhanced sonic detail. The High Driving mode provides powerful and stable output, similar to a four-wheel drive car confidently navigating rough terrain. This mode is designed to accurately reproduce even the most delicate sonic details, allowing you to enjoy deeper, clearer, more immersive music.
Minimized delay with patented Enhanced Signal Alignment (ESA) technology
The SP4000 incorporates innovative ESA technology, which effectively addresses a persistent issue in audio: the time lag phenomenon that arises when various frequencies traverse an internal system. This phenomenon occurs when different frequencies reach the output device at slightly different intervals, leading to delays. Essentially, it refers to the situation where frequencies within an audio signal do not synchronize in their arrival times, which can compromise clarity, imaging, and timing. The ESA technology in the SP4000 synchronizes frequency signals to ensure they arrive more uniformly, thereby reducing frequency distortion and greatly enhancing sound clarity and purity. Furthermore, the A&ultima SP4000 power supply features a newly designed LDO (Low Dropout) regulator that minimizes noise by up to 97% compared to earlier models. LDO regulators are high-performance components typically utilized in precision medical and 5G communication devices, aiding in battery voltage stabilization and noise suppression for a cleaner audio experience. In light of the increasing trend towards music streaming, Astell&Kern has introduced comprehensive support for Android OS, allowing users to install any app from the Google Play Store on their devices for the first time. Astell&Kern has also addressed the Android OS sampling limitation (SRC) with its proprietary personalization technology, ADP (Astell&Kern Direct Path), ensuring bit-perfect, lossless playback even in streaming scenarios, thus providing the highest sound quality during music playback. Alongside exceptional audio performance, the SP4000 enhances user experience, representing a significant advancement in the evolution of next-generation digital audio players.
New advanced Digital Audio Remaster (DAR) technology
The SP4000 features Advanced DAR, the second generation of Astell&Kern’s Digital Audio Remaster technology, which enhances sound quality to be more natural and refined. Initially, the SP4000 employs Virtual Sound Extender (VSE) to restore lost harmonics before sending the audio file to the DAR engine, thereby improving sound quality in the first phase. The advanced DAR engine then conducts a second upsampling process with enhanced precision and thoroughness. This multi-step method enables listeners to experience a richer, more immersive sound that closely resembles the original recording. To ensure optimal sound quality, the SP4000 incorporates high-quality Any Layer HDI (High-Density Interconnect) PCB technology. This sophisticated circuit board, commonly found in smartphones and premium electronic devices, allows for the precise design of complex circuits in a compact format, reducing signal loss and resulting in a more detailed and refined sound. Additionally, the SP4000 is fitted with a precision-engineered Shield Can that effectively blocks various noise types and electromagnetic interference that could disrupt audio quality. The 99.9% pure copper Shield Can, a first for Astell&Kern, not only offers outstanding shielding but also enhances sound clarity and distinction like never before.
New graphical user interface
The SP4000 features an upgraded user interface that merges functionality with emotional engagement. The main display showcases an engaging animation, allowing an LP to appear as if it is sliding in and out while browsing albums, transforming music selection into a visually captivating and tactile experience. This interface maintains A&K’s signature Crimson theme, reflecting the brand’s identity and encapsulating its unique emotional essence within a sophisticated, contemporary design.
A&K’s Crimson theme emphasizes simplicity and unobtrusiveness, prioritizing usability and intuitiveness. Three core principles—Edge, Simple, and Sensibility—were implemented to enhance usability and improve clarity, showcasing a style distinctive to A&K. The chosen black and red color scheme aims to minimize eye strain, optimize battery life, and reduce heat output.
Included with the SP4000 is a premium leather case, crafted from shrunk calf leather by Perlinger, a renowned German leather manufacturer established in 1864, known for its five generations of craftsmanship. Perlinger provides the finest leather to luxury brands globally, blending centuries-old traditions with modern techniques.
The shrunken calf leather used for the cover is sourced from the soft, delicate hides of calves under one year old. It undergoes a chrome tanning process to maintain its natural texture, followed by a unique shrinking method (without heat) to preserve the organic grain and wrinkles. After an aniline dyeing process, Perlinger’s proprietary pigments are applied to achieve a rich, vibrant hue. Their advanced anti-aging treatment guarantees the longevity of this deep color, enhancing the SP4000 with a leather cover that exemplifies lasting beauty, durability, and luxury.
Astell& Kern A&ultima SP4000 specifications
The device is equipped with 256GB of internal storage and supports microSD cards up to 1.5TB. It features dual-band 2.4/5GHz a/b/g/n/ac Wi-Fi, DLNA networking, a USB digital audio output, and USB-C for data transfer and charging. Additionally, the SP4000 can function as a USB DAC for both Mac and Windows PCs. Its 6-inch touchscreen display boasts a resolution of 2160×1080 pixels, capable of up to 2K resolution. The SP4000 supports high-resolution PCM music playback natively, reaching up to 32-bit, 768kHz, and DSD512. ReplayGain technology ensures consistent playback volume across various music tracks, while AK File Drop enables wireless file transfers from a PC, smartphone, or FTP program on the same network, facilitating music file management wirelessly.
In terms of Bluetooth capabilities, the A&ultima SP4000 is compatible with both aptX Adaptive and LDAC codecs, providing audiophiles with enhanced options for wireless 24-bit audio playback. With BT Sink, the SP4000 can connect to external devices via Bluetooth, acting as a Bluetooth DAC, allowing high-quality playback from devices like smartphones, leveraging the SP4000’s advanced audio features. The SP4000 is set to receive Roon Ready support pending testing and certification by Roon Labs. Thanks to Qualcomm QC 3.0 fast charging technology, the DAP charges more quickly and efficiently than earlier models, reaching a full charge in approximately 4 hours and offering around 10 hours of continuous music playback.
To combat ear fatigue during prolonged listening sessions, the SP4000 includes a Crossfeed setting that blends signals from both channels with a time delay, creating a soundstage akin to listening to music through large speakers in a room. Users can fine-tune this effect with detailed controls such as Shelf Cutoff, Shelf Gain, and Mixer Level.
