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Product: Fosi ZA3 - integrated amplifier
Manufacturer: Fosi Audio - China
Approx. price: ZA3 with 48V/5A PSU: €160
Reviewer: Lucio Cadeddu - TNT-Audio Italy
Reviewed: May, 2024

Foreword

As Fosi Audio had already mentioned to our reporter Cora during the reportage from their headquarters in China, they were planning to release many new products in the next few years. So, shortly after the release of the V3 integrated amplifier, the ZA3 is already here, and it is - more or less - a V3 with some additional features and a different cabinet.

A closer look

The ZA3 is nothing other than a V3 with the addition of a 300Hz filtered subwoofer output, both RCA and balanced XLR line inputs, a MONO button and a larger cabinet to accommodate these additional features. A remote control is still missing, a much wiser choice instead of the useless balanced inputs, given that the typical buyer of a 100€ amp will hardly use a source with balanced outputs. The rest, essentially, has remained unchanged. The presence of the MONO button allows you to use only one ZA3 per channel, but obviously you need to insert a preamplifier upstream, since it is impossible to adjust the volume for the two channels in a perfectly identical way using two different potentiometers. It is hence necessary to set the two volume pots to their max and adjust everything with the preamp knob alone. Honestly, it doesn't seem like a good idea to have three volume pots between the source and the output, since even one single volume pot is harmful to the signal. The use of these ZA3 amplifiers as mono power amplifiers, therefore, doesn't seem a very good idea, in my humble opinion. More about this later.

In any case, I tested the ZA3 as an integrated amp in comparison with its brother V3 and then the pair of mono'ed ZA3s compared with other power amplifiers, in particular a pair of ZeroZone IRS2092 Class D monoblocks.

The technical specifications, for which I refer to the Fosi Audio official page, claim a power of 180 watts per channel on 4Ω and 235 watts in mono, always on 4Ω. This is when powered with the 48 volts PSU, which is the standard power supply. Otherwise the values ​​drop if the 32V power supply is used. The real data, obviously, must be read and understood well in the datasheet of the chip used, which is the same as in the V3. By lowering the tolerance on the rate of harmonic distortion to a more realistic 0.1% (and not 1%, let alone 10%) these astonishing numbers become more realistic: see the “watt vs THD” graph in the V3 test.

Newer is not always better

Tested as integrated amplifier. The more logical comparison was performed, obviously, with its little brother V3. Having two identical ZA3s available, I used the same 48V power supply for both the ZA3 and the V3. Consequently, the comparison has been exactly on par.

The tonal balance does not differ much, and this doesn't come as a surprise: same power supply, same chip and essentially the same circuit. Something changes, however, and unfortunately all for the worse. The V3 is harmonically richer, especially in the high range, the sound presentation is a little more large and, overall, the music flows in a less artificial way.

I wonder if Fosi listened to the ZA3 in comparison with the V3. I doubt it, because they would have avoided releasing it. The differences between the two amps are not striking, and only emerge when the amps are tested in an extremely revealing set-up. Therefore, anyone who plans to judge them with modest speakers, placed as best as they they can (perhaps on a desk, next to the PC monitor) and in an unsuitable environment, it would be better he refrains from writing something about the sound of these two amps. In this situation, realistically, the two amplifiers would sound _exactly_ the same.

I wondered what the causes of these differences could be. It is possible that the additional circuits (balanced inputs, subwoofer output and trigger circuit) force the signal to travel a longer path, a long and tortuous path that realistically drains useful resources from the PSU (read: current). The V3, instead, is an extremely simple device, and this can be felt in the fluidity with which it manages the sound message.

Tested as mono power amp. Let me start with an obvious remark: a pair of ZA3s costs €300 approximately, practically as much as a pair of ZeroZone power amps. Logically, therefore, the quality/price ratio should be more or less in the same league, even taking into account the additional features of the ZA3. Unfortunately, the comparison has been merciless: the ZeroZone pair outclasses the two ZA3s in practically every aspect of audio reproduction: the low range is not only more powerful and controlled, but also significantly deeper. The mid-high range is cleaner, harmonically richer and less electronic, if you understand what I mean. Everything sounds more fluid and natural. Overall dynamics are vastly better: the sound of ZeroZone has much more impact, punch and control. Not only, it is faster, with more precise attacks and decays.

The three-dimensional stereo image is wider, crystal clear and realistic. In other words, I haven't found a single reason to prefer the ZA3 pair to the ZeroZone pair. The differences, in this second case, are not nuances as in the previous comparison, as they are utterly evident.

Remarks and complaints

1. Like the V3, being a minimalist amp, the ZA3 lacks features that are almost indispensable today, such as an internal DAC, a remote control and a headphone output. Yes, it adds other features, such as balanced inputs and the possibility of mono operation, but unfortunately these extras are absolutely useless in this price class. The line output for the subwoofer is uselessly filtered (active subwoofers have an internal electronic filter!)
2. Being a very compact object, albeit slightly larger than the V3, the room for rear connections is limited, given that the extra room has been used to accommodate those bulky XLR inputs, for example.
3. The entire cabinet is designed to dissipate heat. Actually, even after hours of full power operation, it did not show any particular overheating. Give it at least 5 minutes to reach the optimal operating temperature.
4. Sonically, it reminds me a lot of the V3, but evidently something is (slightly) wrong with it. Perhaps the presence of the additional circuits does some damage. The V3 sounds better overall, period. Even in this case, one should not expect a warm and soft sound presentation, but a lively, open and dynamic one. Using them as monoblocks is a no-no, as the cost doubles and a pair of ZA3 become dangerously close to a pair of ZeroZone power amps, which are not only much more powerful, but they also sound significantly better, in every parameter, particularly in the low range, in terms of three-dimensional imaging and in the mid-high range.

Availability

The ZA3 is available in the usual online stores, both on Amazon, Aliexpress and on the Fosi Audio official website. On Aliexpress you can sometimes get a lower price, but at the risk of having to pay customs fees (depending on where you live and your luck).

Conclusions

The Fosi ZA3 is a bizarre component, apparently designed to respond to the requests of a certain type of users who wanted a real subwoofer output which, however, being filtered, is quite useless. Moreover, I would like to know who could ever request balanced inputs in this price range! They are pure nonsense. Putting the ZA3 in mono is useless, as well.

Let me state this clearly: if you have a V3, hold on to it, because a ZA3 will not sound better. Actually, it sounds slightly worse. If you don't already own a V3 and you would like the additional features that the ZA3 offers, give it a thought. If you need two small mono power amps, they already exist: the V3 MONO. Honestly, the ZA3 design and release seems like a clumsy marketing operation and nothing more. Companies should plan to design and build what THEY believe is necessary or really new, or even an upgrade of an existing component. They should avoid listening to naive customers, YouTubers or forumphiles who fill web fora with tons of pure garbage and nonsense.

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Copyright 2024 Lucio Cadeddu - direttore@tnt-audio.com - www.tnt-audio.com

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