There are now hundreds of small Chinese companies producing high-performance mini hi-fi equipment by quickly leveraging the latest innovations in electronics in areas such as digital-to-analog conversion and class D amplification. Some of these companies, for example Topping, S.M.S.L., and Gustard, have for years been considered among the best manufacturers of affordable audio equipment. Others are rapidly making their way into the hearts of enthusiasts thanks to new products that are extremely high-performing and built with the needs and suggestions of true Hi-Fi enthusiasts in mind. This is the case with Fosi Audio, a young brand founded in 2017 that in just a few years has become highly appreciated by audiophiles worldwide.
In this article we describe our test of the FOSI Audio V3 Mono, class D monoblock power amplifiers based on the TPA3255 chip that have very few competitors in their price range.
Part of Fosi Audio’s recent success is due precisely to a range of amplifiers based on this Texas Instruments chip, considered by many to be the best low-cost class D amplification solution currently available. At present, the Fosi catalog includes as many as five amplifiers based on the TPA3255: the BT20A Pro (with Bluetooth and bass/treble control), the BT30D Pro (with additional subwoofer management), the V3 (with selected components, aimed at audiophiles), the ZDA3 (larger and capable of operating in both stereo and mono mode), and finally the V3 Mono, the subject of this review.
The V3 Mono is a class D power amplifier based on the TPA3255 chip, designed for a single channel and without volume control. It must therefore be used together with some kind of preamplifier. Typically, two V3 Mono units are used to amplify a stereo system equipped with a preamplifier (or even simply a DAC capable of operating as a preamp). It is also possible to use multiple V3 Mono units to amplify each channel of a home theater system.
Currently, the V3 Mono costs about 150 euros per unit.
For those who need a pair of V3 Mono units to amplify their Hi-Fi system, it may be more convenient to purchase the kit consisting of two V3 Mono units (powered by a single 48V/10A power supply) and a power filter.
The V3 Mono comes in a simple black cardboard box containing the amplifier and a generous 48V/5A power supply, almost larger than the amplifier itself. The dimensions of the V3 Mono are 14.2 x 10.7 x 4.1 cm, incredibly small for a power amplifier. However, the overall footprint of a system composed of two V3 Mono units, two large power supplies, and related cables is not negligible and is only slightly smaller than that of a small traditional stereo integrated amplifier.
The V3 Mono is built in a very simple and robust way. On the front there is a small red LED and two switches: the one on the right toggles the device between on/off/AUTO modes, while the other selects XLR or RCA input. Leaving the device in “AUTO” mode keeps the V3 Mono in low-consumption standby, turning on quickly when a signal is detected and returning to standby after a few minutes of inactivity. This feature is extremely convenient and useful: it allows you not to worry about switching power amplifiers on and makes it possible to place them in hidden or hard-to-reach locations. On the back there are speaker connectors that accept banana plugs or bare wire, RCA and XLR inputs, and a switch that allows setting RCA gain to +31 or +25 dB, useful for optimizing volume control on your preamplifier.
Internally, the V3 Mono relies on high-quality Japanese components: ELNA and NICHICON capacitors, Sumida inductors. Compared to the stereo version, the V3 Mono also implements a PFFB (Post Filter Feedback) circuit that helps solve one of the issues of class D amplification: variation in high-frequency response depending on the load. Thanks to this circuit, the V3 Mono performs optimally even with low-impedance speakers that are difficult to drive.
Another noteworthy feature is the ability to replace the stock operational amplifiers (NE5532) with others, experimenting with their different effects on sound. This will certainly appeal to more hands-on users.
Fosi states that the V3 Mono was designed taking into account feedback and suggestions received for the V3 stereo and ZD3, and the results are evident: all the included features are useful, practical, and well designed.
The Fosi Audio V3 Mono declares a power output of 240W into 4 ohms and 120W into 8 ohms. Keeping distortion at very low levels, the actual continuous power output with a 48V supply is just under 100W into 8 ohms: an impressive figure for a mini class D amplifier.
We tested the V3 Mono with Indiana Line Nota 260XL and Lonpoo LP42 speakers, using several DACs with preamp functionality, and compared them with other mini class D amplifiers based on popular chips: a Sonic Impact T-Amp, a Fosi Audio BT10A, a Sure TPA3116 board, and cheap Chinese boards based on TK2050 and TPA3255 chips. We wanted to see how much a pair of V3 Mono units could improve a budget hi-fi system. The answer was a lot: compared to the other class D amplifiers tested, the V3 Mono stands out immediately for its powerful, controlled, and articulate bass. The mids are clean and well-defined, and the highs are never harsh or artificial. Another very satisfying aspect is the soundstage: wide, stable, and deep.
In conclusion, we really liked the Fosi Audio V3 Mono. At the current selling price (around 300 euros for a pair), we do not believe there are other power amplifiers with comparable features. If you are looking for a mini integrated amplifier with excellent performance at an even lower price, we recommend taking a look at the V3 (stereo) from Fosi Audio. We were not able to test it, but given the similarities in components, it could be a real bargain and is currently available for under 100 euros.
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