 It has been only four months since I reviewed the Allo Katana Raspberry Pi bass, streamer and network bridge. And quite soon thereafter there were reports on halted production due to sound quality issues. I still own that Katana player and I stick to my opinion that it was the best Raspberry Pi DAC up till then. But now Allo introduced version 1.2 of the Katana player in two variants. One optimized for sound quality and one optimized for low total harmonic distortion and noise measurements. They also sent me the isolator version 1.3 so I got a nice job cut out for me since to exchange one DAC board for the other means taking the stack of boards apart and the same goes for the isolator. But let's start at the beginning. In August I made an extensive video on the thoughts behind the Katana stack of boards and I suggest you watch that video for the principle hasn't changed. But in short the Katana player uses three printed circuit boards, one for the Katana digital to analog converter board that uses the ESS9038 Q2M DAC chip and ultra low noise jitter clocks from NDK. The second board holds the analog output circuits using discrete op amps instead of integrated circuits. Allo teamed up with Sparkles Labs for these amps. The third board holds the microcontroller that can be said to do a number of reconstruction filters by changing dip switch settings of or over software that facilitates this. Regular viewers know the importance of clean power for the DA conversion and analog audio. One of the nice things about the Katana stack is that you can play around with several ways of powering, using one to four separate power supplies. Roughly one 5 volts DC for each board and a plus and minus 15 volts DC for the op amps on the analog output board. Again, see the video on the previous version of the Katana. I have used two power supplies, one audiophile power supply by sBooster for anything audio and one cheap switch mode power supply for the Raspberry Pi. I alternatively used the Allo battery pack that holds two times two 18650 batteries instead of the sBooster. Using two power supplies does isolate the power buses but not the digital buses between the Raspberry Pi and the Katana. The isolator is an optional board that is installed between the Raspberry Pi and the Katana board. It holds a set of four digital isolator chips that fully separate the primary and secondary side. So the board knows a dirty side and a clean side. The dirty side can be powered from the Raspberry Pi but it also has its own power input in the shape of a USB Type-C connector. A jumper bridges or separates the dirty side of the isolator and the Raspberry Pi. The preferred way of powering both is connecting the power supply to the USB Type-C connector on the isolator and bridging the jumper to feed the Raspberry Pi from there. For all tests I used the Rupee software that turns the Raspberry Pi into a Roon endpoint. Roon was said to be fully bit perfect so no volume control and no DSP functions. I chose the appetizing filter on the Katana and started comparing the Katana version 1.1, the one I reviewed four months ago, with the new version 1.2, the sound quality optimized version. And I must say that the improvement was clear right away. Improvements involved especially the mid and high ranges, offering higher resolution and less stress. Especially the highs were cleaner. Overall the sound is richer and more agreeable. Again, the old version wasn't bad, not bad at all. But version 1.2 brings the sound closer to that of the chord Hugo driven by the LOUS bridge as in my setup 2. This version is the same as the version that is optimized for sound quality with the exception of the analog stage that is optimized for better measurement of total harmonic distortion plus noise, THD plus N abbreviated. As often, reducing THD plus N also reduces the sound quality. In this case it makes the music less emerging, colder. I don't know what was done technically to reduce THD plus N but my guess is that it influences time related behavior. So if you buy a Katana to watch music on a scope, you should go for this variant. All others should go for the sound optimized version. So I took the stack apart again, replaced the DAC board with the sound optimized version and added the isolator board. The dirty side of the isolator was powered directly using a cheap switch mode power supply. From there the Raspberry Pi was powered too. The clean side was powered from the Katana stack via the USB-C connector on the processor board. Given the price of 47 USD, 40 USD when bored together with the Katana stack, this is a no-brainer. It further refines the sound, reduces stress and improves on pace and rhythm. Don't expect a huge difference. It's a refinement but surely worth the extra 40 USD. Let me be clear about buying advice. If you buy the Katana player with isolator set, including case, a microSD card, a cheap power supply and a battery set, including a charger, you spend around 475 USD. An iFi iPower audiophile power supply will be somewhat cheaper and more convenient. If you go for the S-booster, it's slightly over 700 USD for the set. Sound wise it is a sound investment, pun intended. But please do realize that you end up with a collection of gear, the Katana stack and at least two power supplies or one power supply, a wall wart type and a battery holder with batteries that have to be charged frequently. So you need a charger too. Then you have to flash a microSD card with the software of choice and have a remote, a smartphone or tablet find the Katana hardware. If you think that's doable, then the Katana 1.2 with isolator offers a lot of sound quality while the functionality depends on the software chosen. In my case the fantastic Rune software was used. On the yellow side you find a comprehensive list of software that works with the Katana hardware. If computers are not your thing, you better settle for a ready to use product. See my playlists for network bridges and networked audio players. Links in the show notes. While finishing this program I already worked on two networked audio players in a somewhat higher category, the Auralic Aries G1 and the AudioLab 8300CDQ. If you are interested in these reviews or other reviews like this one, subscribe to my channel or follow me on social media. I will let you know when they are out. 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