 Already months ago, the SBooster Best of Two Worlds Power & Precision Eco MK2 linear power supply was announced. But perfection takes time and finally delivery to place. The SBooster products have been audiophile linear power supplies from the start when they made their first model the best of two worlds made for the squeeze box. In 2015 they introduced a much larger model named SBooster Best of Two Worlds Power & Precision Eco. This is now being replaced by the MK2 version. The initial model was first available as 5 volts DC model but over time models became available at any voltage between 5 and 24 volts DC. There are two kinds of power supplies, linear and switch mode. The linear power supply, like the SBooster, have been around since the beginning of electronics. Usually these power supplies were integrated in the devices they power. But when the world became smaller and smaller, manufacturers wanted to conquer the other continents. There was not without complications though, since voltages, mains frequencies and safety legislations differ from continent to continent or even from country to country. Especially for the cheaper equipment they didn't pay to get local safety approval. That is where the external power supply, the World War II power brick, comes into play. The manufacturer of, let's say, a network player buys certified power supplies at the right mains voltage and the right local approval from a local manufacturer, puts it in a box with a streamer and now the streamer is a low voltage DC power device that needs no certification while the external power supply was already certified. When the switch mode power supply came to market, due to their way of working they work at any mains voltage. Asian manufacturers today offer these wall wards at any output voltage in amperage, certified for world use and at extremely low prices. It seems to good to be true and it is, at least for serious audio. Switch mode power supplies switched the desired voltage on and off at a very high frequency, often 200 kHz or higher. Since there will be no current for the voltages already switched off when a current even considers to get going, a very tiny step down transformer can be used since there is no risk of overheating. A rectifier and a filter smears out the pulses to DC. It's like laying drops of glue on a 4x3 and then using a spatula to even it out. The big advantage is that the small transformer is immensely cheaper than the transformer needed for a linear power supply. Another advantage is that such a switch mode power supply is capable of delivering power instantly by design, as where with linear power supplies it needs a clever design to achieve that. Switch mode power supplies have only one disadvantage. They are by nature extremely noisy and it takes a lot of effort to reduce the noise to levels that are acceptable for critical audio applications. It can be done, as you might have seen in my review of the Optone Audio UltraCAPS LPS-1 power supply and I have compared the SOtM SPS-500 power supply to the S-booster in the SOtM SPS-200 Ultra Review. About the same performance but both switch mode power supplies are more expensive. And yes, both are specified to deliver a higher current. But where the specified current for the switch mode is the absolute ceiling, linear designs still have headroom above the specified maximum current to cope with short peaks. One last remark on switch mode power supplies. Before to average designs not only can have heavily polluted DC output, they can also pollute the mains and so have a negative influence on other components in your stereo. A notorious example was the first Super Audio CD player by Philips. That essentially was a very good Merence design, Philips own Merence at that time. But then the Influence Marketing Department of Philips wanted a cheap switch mode power supply to keep the price at a certain level. If you only plugged in the mains connector of that player somewhere close to your stereo, the sound quality degraded drastically. So even with the audio connections from the SACD player not connected, thus playing from another source. Therefore I always use mains filters for connecting switch mode power supplies. Not to keep the pollution from entering the switch mode power supply but to prevent the switch mode power supply from polluting my mains. Good switch mode designs don't need to cause this but the number of good switch mode designs is limited. The basic architecture of the MK2 has not changed from that of its predecessor. Let's open both and show them next to each other. There is little difference at first sight. You see the power switch and the IAC main socket directly mounted on a PCB holding the twin stage mains filter and earth line choke. These clean the input from high frequency pollution. There are switches to set the mains voltage of choice. These are set prior to shipping to the right voltage for the destination and a sticker on the outside indicates the setting. The transformer that follows is a custom made audio grade toroidal model. The second side of the transformer feeds the rectifiers, the smoothing capacitors and the voltage regulator. And there is a switch to select the output voltages that are very close together, like 9 and 10 volts or 12, 13 and 13.5 volts, depending on the model of choice. So what's the difference in the MK2? There is a different fuse holder, the color of the PCB differs and the cooling profile of the voltage regulator appears to be slightly thicker. That sounds trivial but things are not what they appear. The transformer now has not only electrostatic shielding but also HF magnetic shielding. A transformer specialist told me that the magnetic shielding is not trivial. The PCBs are redesigned to double sided while now two ounce copper issues, twice as thick as usual. There also is a gold-plated finish, as can be seen here. The internal wiring is all high quality silver-plated copper with Teflon insulation. The output cable now has oxygen free copper conductors, braided shielding and a braided sleeve. The bespoke DC connectors are gold-plated and all cables and DC plugs are soldered with high quality silver solder. And the production is brought back from China to Europe, where more attention to detail is given, according to S-Booster. Yeah, the sound. Since I use the S-Booster products for both my SOtMSMS200 Ultra Neo and the MiTech Brooklyn I have replaced both with the MK2 version and immediately had a problem. How can I convey this experience to you in a credible manner? You might have the idea that I don't know all, but I don't. I'm just slightly ahead of most of you. The changes that my SET-1 underwent over the last two years brought an immense increase in sound quality. From the S-MS200 to the Ultra, from the cord Hugo to the MiTech Brooklyn, all S-Booster powered, then the S-MS200 Ultra Neo and now the MK2 S-Boosters. The S-MS200 Ultra was a giant leap, the Brooklyn a clear refinement and every other step another refinement. I already passed the point of stating that it all sounds analog. But again the MK2s bring it another step further. The voices are yet another step closer to perfection. Transitions are free and fast, the background is yet further to the back. The spaciousness of some recordings is now at a level that I won't play them when my brother visits, since he has false anxiety. And it's all credible. It sounds natural. Those got tighter too and I have never heard a glockenspiel this clean. But we must see it in perspective of course. The sound of my SET-1 isn't that great due to the S-Booster MK2, it's an accumulation of quality. Working on my SET-1 brought me to a very well tweaked system where the slightest improvement becomes clear immediately. In my SET-3 the difference between the MK1 and the MK2 will be a lot smaller. I couldn't try this since I only had a 9 and a 12 volt version of the MK2 and the Raspberry Pi needs 5 volts DC. In my SET-2 it must already be well audible. Again that's an educated guess. It's all about matching qualities. Putting racing tires on a Kia Picanto won't bring you a race car. And for those that own the same front end, the biggest difference I got was by replacing the MK1 S-Booster on the MiTech. The one on the SOtM Neo also gave clear improvement but somewhat less. I spoke to Wibrand Rijer who designs the S-Booster and he told me that the build quality of the Bulgarian factory is clearly higher and that alone does make a clear difference. After that the better components and some other tweaking, I'm sure he didn't tell me all he did, did indeed improve the sound quality when used in my SET-1 and I'm sure also in my SET-2. Just one remark remains. Although I love the company and their product very much, I'm not married to S-Booster. If another manufacturer thinks he has even a better product or equal product at a lower price I'm very interested in doing a review. And if that's your interest too, subscribe to this channel or follow me on the social media. If you liked this video, please consider supporting the channel through Patreon or Paypal. Any financial support is much appreciated. The links are in the comments below this video in YouTube. Help me to help even more people enjoy music at home by telling your friends on the web about this channel. I am Hans Beekhuyzen, thank you for watching and see you in the next show or on the chbproject.com. And whatever you do, enjoy the music.