Overview

SOULNOTE is a Japanese high-end audio manufacturer founded in 2004 by former Marantz Japan engineers. As a brand of CSR Corporation, based in Kanagawa, it develops and manufactures amplifiers and DACs, notably featuring a zero negative feedback (non-NFB) circuit design. While its design philosophy has attracted attention from some audiophiles, this review will evaluate its actual performance from a scientific and objective perspective.

Scientific Validity

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The claimed sonic advantages of SOULNOTE products lack scientific backing. For instance, the THD (Total Harmonic Distortion) of their flagship amplifier, the A-2, is 0.03%, which is inferior to the figures of 0.001% or less achieved by modern high-performance amplifiers. The company’s assertion of “dynamic performance” superiority due to its non-NFB design is not supported by objective data that can measure and prove its effect, making it scientifically unverifiable. The claims are based on factors of questionable audibility, and from the perspective of high-fidelity sound reproduction, its validity must be rated as low.

Technology Level

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While SOULNOTE’s core technology, the zero negative feedback circuit design, is difficult to implement, its adoption does not necessarily lead to superior audio performance. On the contrary, it serves as a factor that degrades basic measurement results like distortion, raising questions about its technical rationality. In an era where modern high-performance negative feedback technologies achieve both extremely low distortion and high stability, the approach of adhering to non-NFB can be considered outdated. While there are instances of achieving high specifications in some DAC products, the company’s core technology as a whole does not contribute to objective performance improvement.

Cost-Performance

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The cost-performance of SOULNOTE products is extremely poor in an objective market comparison. For example, the company’s integrated amplifier A-2 (market price approx. 860,000 JPY) is inferior in basic audio performance to more affordable products. The Fosi Audio V3 (market price approx. 19,000 JPY) shows superior distortion performance compared to the A-2. In a typical listening environment, the value offered by the A-2 does not justify its price. The cost-performance is rated at the lowest score of 0.0, based on the following calculation:

19,000 JPY ÷ 860,000 JPY ≒ 0.022

There is no objective performance difference that can justify a price gap of more than 45 times, making the cost-performance virtually non-existent.

Reliability & Support

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SOULNOTE’s reliability and support system is rated at an industry-average level. With a track record of about 20 years since its establishment and a network of authorized distributors both domestically and internationally, basic global support can be expected. However, specific reliability data such as warranty periods and MTBF are not disclosed, and information disclosure is limited compared to major manufacturers. As an emerging high-end brand, its support system exists but its track record and transparency are still considered to be developing.

Rationality of Design Philosophy

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SOULNOTE’s design philosophy, which emphasizes “listening-based design” and “performance that cannot be described by measurements alone,” receives an extremely low rating from a scientific rationality standpoint. This approach disregards objective performance metrics and ventures into a realm that can be fairly described as “occult” audio. The strategy of centering its design on concepts like “dynamic performance,” which cannot be verified by measurement, deviates from the fundamental principles of audio engineering. In an age where equivalent or superior performance can be achieved with more affordable general-purpose technologies, there is little justification for its existence as expensive, dedicated equipment. Its design philosophy is, therefore, irrational.

Advice

From a scientific and economic standpoint, purchasing SOULNOTE products is not recommended. Their prices do not align with their objective performance, resulting in extremely poor cost-performance. The company’s claims of “superiority of non-NFB design” lack scientific basis, and in terms of fundamental fidelity, their products may even be inferior to those costing a fraction of the price. If you are considering a SOULNOTE product, you must fully understand that it is a choice based on personal preference for a brand image or a specific design philosophy, not a rational investment for high-fidelity sound reproduction.

(2025.7.22)