 Aloe's new DAC is remarkable in several ways. It is a stack of three printed circuit boards and the price in Europe is about €260. The US price is $249. As far as I know, a new price record. That's no problem, provided it sounds accordingly. Aloe products have impressed me before. Yes, they cost more than other popular products but they perform better too. The Katana is even more costly than the previous Aloe DACs. At $329 you get a Katana set of boards, a Raspberry Pi 3B, a microSD card, a switching mode power supply in a clear or black acrylic case. But you can also buy the three Katana boards as a set if you already have a Raspberry Pi and want to arrange the housing and power supply yourself. As said, the Katana DAC is spread over three boards. The one mounted on the Raspberry Pi is the board that houses the ESS Sabre 9038 Q2M DAC chip, well shielded just as the very good NDK NZ2520 SDA crystal oscillator. It also holds a print connector for an external 5 volt power supply. It is at a very inconvenient place and the solution Aloe came up with is a matching connector with wires sticking through a hole in the optional acrylic housing. The jumper on the left might have to be removed then, depending on the power option you choose. The connector here is to connect to the up and board and is part of the GPIO bus. The connector further down feeds the analog outputs of the DAC chip to the up and board above. There also is a power LED. On the flip side we find the full GPIO connector for connecting with the Raspberry Pi and two super capacitors. The analog part of the DAC Aloe partnered with Sparx Labs that is specialized in discrete op-amps, which is short for operational amplifiers. Usually integrated circuits are used in this class of products. Building discrete amplifiers, meaning build using discrete transistors instead of transistors integrated in a chip, has always been a better way to go but had relatively high building costs. Using contemporary surface mount technology, building time is clearly reduced. The designer has chosen to set the DC offset manually, more precise but labor intensive way to go. Aloe warns against changing the setting of these trim pots. The up and board outputs both single ended audio on RCA and balanced audio to soldering islands to which wires to XLR connectors can be soldered. The standard housing does not have the space to mount XLRs. The next board, the microcontroller board, is connected to this bus and the microcontroller feeds the op-amp board plus and minus 15 volts DC for proper headroom and slew rate. When we look at the bottom side we see the GPIO bus and the connector that receives the analog audio from the Katana DAC board. Most modern DACs have a microcontroller. It is where for instance the digital filters are executed. Most DAC chips offer their own in-chip filtering but external processors are more powerful, enabling better sounding filters. The microcontroller board also contains the electronics that transforms the single 5 volt DC into plus and minus 15 volts DC, used to power the op-amp board. The 5 volt DC input is a USB-C connector. If you have an audio grade plus and minus 15 volts DC power supply, you can change these jumper settings and connect that power supply here. The DIP switches let you choose a fixed setting to 1 of 7 reconstruction filters or enable filter change by the player software. If we flip the board we see the GPIO bus and the connector that feeds the plus and minus 15 volts DC to the op-amp board. Some people thought that soldering a printer header to a DAC board and so powering the DAC board directly was over the top. Well, these people better brace themselves for there are six ways to power the Katana using one to three power supplies. You can use a single power supply and connect it to either the microprocessor board or the Katana. When you want to use two power supplies you can either power the Katana and Raspberry Pi or the microprocessor and the Raspberry Pi. But wait, there is more. Use three power supplies and connect them to the Katana, the microprocessor and the Raspberry Pi. And then you can choose to power the op-amp using the plus and minus 15 volt power supply. Funny enough, each power connection has its own connector. The Raspberry Pi uses the micro-USB connector, the Katana uses the print connector with attached to it the two non-terminated wires and the microprocessor board uses USB-C and a print connector for the plus and minus 15 volt power supply. Allo advises a nice way of installing all kinds of software, DietPi. This is an image that you write to the microSD card using a program like Etcher. You then stick the microSD card in the Raspberry Pi, connect a monitor keyboard and network to the Pi and start it up. Setting up will take considerable time but then you are prompted to log in and you simply type the indicated username, enter the indicated password and enter again. Once more some alphabet soup raises the screen until it turns blue with a classic looking menu in the middle. The possibilities here are titanic so if you want to explore, please feel free. I will only show you how to install a music player of the Likings. Use the arrow down key on the keyboard to go to the player you want and press the spacebar to select and when you have chosen the player or players you want, hit the tap key and go to OK and enter. This will bring you back to the software menu. Scroll down to install and confirm the installation. After again flashy instructions flying over the screen you will return to the menu again. If you don't need to use DietPi you could also install Volumio Direct since it already has the drivers for the Katana. The same goes for Max2Play, PiCorePlayer, Mood and others as soon as drivers for those are finalised, which should be by the end of July 2018. I have used the Katana with Volumio and as a rune endpoint both installed using DietPi. I have reviewed Volumio 2 not so long ago so for details see that review. I will put a link in the comments. What you don't find in that review is that you can select the reconstruction filter by going to playback options in the setup menu. There is also a DSD Direct mode, all rather nice for a free software player on an affordable Katana kit. As is the enormous amount of languages that are supported and available plugins that can be installed by simply clicking the install button. Volumio works like a charm on the Katana. Using the Katana as a rune endpoint is rather uneventful. Use DietPi to install the rune endpoint software and you're done. The implementation is proper and the volume control from within rune works perfectly. An alternative might be RopeA, my favourite rune endpoint software for the Raspberry Pi for it also supports the Raspberry Pi LCD touchscreen. The Katana is not yet in the list of supported hardware but since all other LO products are supported I get that this is only a matter of time. Again, LO sets the standard for Raspberry Pi or to be safe, it's the best I know. Now let me put this in perspective. The Katana, when used with one SBooster SOtM power supply connected to the microcontroller board, fits my setup too and scales in between the LO bus and the cord mojo. Using three power supplies not only is a hassle, you need to connect the power supplies in a given order to have the Katana startup properly. It's also expensive. I don't stock a shipload of 5V SBooster BOTWs so I use the initial smaller model SBooster connected to the microprocessor, the SBooster BOTW, the big one, first generation, to the Katana and the i5 power 5V to the Raspberry Pi. I actually found the sound a tad less. Using two SBoosters and having the Raspberry Pi powered from the microprocessor sounded perhaps slightly more relaxed but I wasn't even sure. What you shouldn't do is use one or more standard 10 euro switching mode power supplies for that will immediately lead to a degraded sound, like harshness or voices and lesser resolution. Just use one audiophile power supply, see my review on those. I will put a link in the comments. Then you have a streamer that costs the same as ready to use streamers by consumer electronics brands but you end up with a better sound, more detailed and spacious. Let me start with a serious warning. Raspberry Pi is often used Linux as operating system, as in this case. And to keep the processor load as low as possible a graphical user interface is left out. This means that if all goes right you have a very fine player at an attractive price. But if something goes wrong you read your own. Of course you might try to find a solution in user groups but if you are not tech savvy you might not speak their language. Plus not all user groups are audio focused, computer cracks might be satisfied when they just hear the music. Don't get me wrong and if you are reactive in a good user group don't feel offended. But I see the casualties, people that never should have started with the Raspberry Pi and want me to give them personal support. I count people, too many requests, too little time. But if you are able to master the secrets of the Raspberry Pi, or just want to try your luck, you get an enormous versatile device that works for many free players, can work as DLNA or UP and PAV renderer, can emulate a squeezebox or be a rune endpoint. The only thing it doesn't support is MQA. By the way, the rune endpoint software is free, the server isn't. Depending on where you live, you can have a complete Cantana player for around 400 euros or less, slightly over 700 euros with a good power supply. And I know of no other system that offers all that for this money. I keep looking for new products and developments. So if you want to follow my quest, subscribe to this channel or follow me on Twitter, Facebook or Google+. If you like this video, please consider supporting the channel through Patreon or PayPal. Any financial support is much appreciated. The links are in the comments. 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 theHBproject.com. And whatever you do, enjoy the music.