Compared to the P3, we have a valid set of inputs since we have three line inputs via RCA connectors and an output to the power amps, again with two RCAs. There is also a dedicated output for a subwoofer. Also on the rear panel we have a slide switch for adjusting the gain on three positions: +3, +6 and +9dB. There is also a lever switch to completely exclude the treble and bass tone controls, plus a connector for the 12V power supply. On the front fascia we have, starting from the left, the power-on switch that also serves to select the inputs, the knobs for controlling the bass, volume and treble and finally the infra-red remote control receiver. The tone controls have a range of ±12dB and a useful zero point through a small click in the rotation. An important novelty is the presence of a remote control that summarizes the main functions of the device: power, mute, volume and input. The remote control is unique for various Fosi Audio products and therefore to use it with the P4 you must press the appropriate button on the remote control.

The specs are very interesting from the point of view of the measurements.

The power supply is external and provided by a small smartphone-style power supply that claims to be of the switching type and provides 12V with 1.5A; I have photographed the two power supplies of the P4 on the left and the P3 on the right because you will see that the one of the P3 will be useful later.

How does it sound?

Connecting and starting up the P4 is very simple and intuitive. Since the device under test was new and the first listening was not exciting, I connected it to my streamer and let it play for about fifty hours. At this point I connected the Burmester preamp to a turntable and started listening with the phono preamp connected directly to the power amps. It is a very hard test to overcome for any preamplifier; believe me, the quality that you get by skipping a level of sound processing is truly surprising; at least a couple of preamplifiers with a lot of zeros in their price were disappointing. After listening carefully to the reference, I inserted the P4 into the chain, so let me summarize my listening impressions below.

• Gain adjustment: I tried the P4 connected to both a pair of NuPrime ST10M and a pair of ZeroZone IRS2092 power amps. The feeling is that as the gain increases the performance worsens in the sense that the sonic characteristics of the P4 become more evident, so the test was always done with the gain set to +3dB. Furthermore, if you use the ZeroZone monoblocks with the gain at +9dB you practically cannot find an acceptable level of rotation of the volume knob because you go from zero to deafening in fractions of a degree of rotation.
• Tone controls: there are some, they raise and lower the treble and bass but for the test they seemed irrelevant so I simply excluded them.
• Background noise: almost non-existent. Excellent performance.
• The overall tonal balance of the P4 is quite open, with a good presence effect.
• Bass range: fast, tight, correctly articulated, a little less musical than my reference.
• Midrange: correct, pleasant. Voices are reproduced correctly. There is a slight hint of “electronicity” in the reproduction that is not present in the original but this area of the acoustic spectrum is probably the strong point of the P4
• High range: correctly extended though a little highlighted compared to the original. However, the reproduction in these frequencies loses the naturalness of my analogue playback system to become very electronic. It seems to listen to a CD. Furthermore, in certain passages, the highs become a little sharp and tiring.
• Virtual stage: excellent width, I would say equal to the original. The depth however is much less in the sense that the P4 brings forward instruments and accompaniments that in the original are far back, leaning against the rear wall. Overall, it is a in your face presentation that can be spectacular at the very beginning but then becomes disappointing.
• Size of instruments and voices: the P4 tends to enlarge instruments with a significant mid-bass range. This gives each one a greater presence but, if there are many instruments playing together, they begin to overlap and this generates a loss of transparency of the sound. If they are all in line in the middle of the room sometimes you can't understand anything anymore. In this area the P4 is at the opposite extreme of the P3 which shrinks each instrument or voice so everything remains very intelligible but the individual ones seem disconnected and not a part of a whole.
• Dynamics: in normal conditions it is good but when dynamic variations occur in a set of instruments then the P4 tends to sound confused. I suspected that the problem was in the power supply and, by chance, I saw that the P3 power supply still has a 12V output but can provide 5A of current, almost three times the power of the standard P4 PSU. The performance of the P4 is much improved and also the depth of the scene has improved. You can find excellent quality 12V linear power supplies online for less than €100 that could be the perfect solution.
• Transparency: overall good in the sense that by changing turntable and cartridge the differences that are clearly heard in the original signal are also clearly recognizable downstream from the P4.

Given the negligible power consumption you can leave it always on but it still sounds good even when cold. The remote control works correctly and is very easy to use; the volume is adjusted in steps and in some cases the jump between two positions could be too wide for your tastes but you can always intervene manually to find the right position. The rear connectors are very close to each other and if you use cables with large connectors you will struggle inserting them. It would be enough if it were 5cm wider and 2cm taller and it would be much more ergonomic but these measurements are the result of a standard extruded case so, given the price, I'd better keep my mouth shut. If you have heavy cables equip yourself with ballast because the weight of a cable can drag everything down from the shelf.

Conclusions