Introduction

Hi All, 

Today we are talking about an interesting speaker amp from Audiophonics, the MPA-S125NC. This is an Ncore NC122MP class D module-based amplifier. The Ncore and Purifi class D amplifier modules are available to manufacturers as an OEM part, which they can then use to put together their own products. These amps can be anything from budget-oriented (like this one) to much more built-out and fancy, as some other manufacturers are. 

The Ncore and Purifi are both designs primarily by Bruno Putzeys, Ncore being his first company, which was then sold, and Purifi being his current company. The general idea of the Ncore and Purifi philosophy is to take Class D amplifiers, long the subject of disdain from audiophiles the world over, and offer sonic performance more in line with the traditional Class A and Class AB amplifiers we are used to seeing. They are also designed to offer exemplary measured performance, though to be honest, I don’t care how something measures if I don’t enjoy listening to it. Thankfully, I’ve really enjoyed my time with the Audiophonics S125NC. 

Class D Headphone Disclaimer

Over my time with the S125NC, I’ve mostly paired it with hard-to-drive headphones, and some speaker use also. This requires a bit of a disclaimer. Class D amps when used with non-speaker-like loads (essentially above 8 ohms) can show increased treble and ultrasonic noise. As such, it’s not recommended to use headphones (especially not high-impedance headphones) with things like the cheaper class D integrated amps from companies like AIYIMA and Fosi. At best you are likely to have increased treble, and at worst you could have potentially unsafe levels of ultrasonic noise past 20khz, which could damage your hearing if it was loud enough. Thankfully the Class D modules from Hypex and Purifi are load invariant and have been shown to have the same frequency response from 1ohm out to an open load on the measurement device at 10,000ohms. Therefore, if you are going to be using a Class D speaker amp to drive headphones, please ensure it is capable and safe to use with headphones like impedances. I’m a big fan of using speaker amps for hard-to-drive headphones, but it’s definitely worth making sure you are going to be ok doing so. These concerns don’t apply to more traditional speaker amplifiers using Class A or AB topologies. 

General Specifications

The S125NC offers a power output of 2x75W into 8 ohms and 2x125W into 4 ohms. It can come with either RCA or XLR inputs, and there is also a slightly more expensive amp from Audiophonics offering the same Ncore modules, with both inputs available in a wider chassis. 

Sonic Performance

So with that disclaimer out of the way. How does the S125NC sound? In one word? Competent. It does everything you need, nothing you don’t, and does it well at a very fair price of 399EUR. 

The bass of the S125NC is pretty much entirely neutral. It’s not a bass monster of an amp, and I never noticed any sort of boost in the low end. It is clean, clear, and precise bass, whilst also being very quick. That is one thing I noticed about the S125NC in an overall sense, it is a very quick, speedy amplifier with precise transients. If you prefer an amp with a more lush and round low end, I would recommend trying a different amp. However, if you prefer a more neutral and quick low-end, the S125NC is worth checking out, especially at its price point. 

The mids of the S125NC are again fairly neutral. Perceptually the lower mids might even be slightly less than neutral, leading to a cooler, less warm presentation. The upper mids however I felt were pretty much entirely neutral and I wasn’t having any issues with nasal vocals or piercing female vocals. Again the fast speedy nature of the amp came through across the entire midrange. 

The treble of the S125NC is again, very neutral. One of the common tropes about the Class D amps of old is overblown, sharp, and grating treble. I really didn’t have any issues with that here. It isn’t rolled off at all, but I honestly didn’t find it to be sharp or bright in any way. It was just clean and clear, presenting what it was fed in a very honest way. 

In terms of technical performance, I was very impressed with the S125NC for a 400EUR MSRP amplifier. Perhaps partly due to its very neutral tuning and clear treble, it conveys detail very well. Imaging is very precise and its transient response is very fast. The one thing it doesn’t have is a massive soundstage. I would describe the soundstage width and depth of the S125NC as being in the middle of the road. It isn’t the smallest staging amp I have heard, but it also isn’t grand and expansive like some amps can be. The overall technical performance of the S125NC was entirely competent, unflappable, and outperformed its price point. It is always nice to find pieces of gear like this that are purely focused on giving you as much performance for your dollar (or euro in this case) as possible. 

Build Quality

The build quality of the S125NC is simple, effective, and well done. The chassis is metal, in a half-size case, long and thin. You have a power button on the front which illuminates white when on, and a pair of XLR inputs on the back. Also on the back are your typical IEC power input, and some very nice binding posts. The binding posts are actually one of my favourite parts of this amp, they are metal, very solid, and work incredibly well. I’ve seen much worse binding posts on much more expensive amplifiers. 10/10 for the binding posts on this amp. There are some vents on the top panel for ventilation, and that’s about it. Very simple, very effective, well done build quality. 

Conclusion

Overall the S125NC has been a pleasure to spend some time with. I would recommend it highly if you are looking for an affordable, medium power power amplifier, either for headphones, or speakers. If you need more power and can bump up your budget 100EUR, you can get another amplifier from Audiophonics in the same chassis, but with the beefier Ncore modules putting out 2x250w into 4ohms. It is a neutral amp, with a medium-sized soundstage, and technical performance that belies its 400EUR price point. I used it with great success with both hard-to-drive headphones and speakers, and it retained its sonic qualities across every transducer I used. The build quality is simple but effective, and if you need both RCA and XLR inputs, there is a slightly more expensive model with a wider chassis that offers both. The binding posts are high quality, made of metal, and a pleasure to use. My time with this amp has made me curious about other implementations of Ncore and Purifi modules, and I hope I can hear others going forward. All in all, I’d recommend the S125NC highly if you are looking for a medium-powered amplifier at this price point. Well done Audiphonics.