I thought this explained it very well
"Horizon360 is our first ever improvement of our flagship Horizon DAC since its creation 3 years ago.This move is mainly enforced by the chip availability limitations. When our “magic” chip got almost depleted and also we started working on Taiko Olympus XDMI interface - we had to decide to make major changes and eventually find a different chip. After searching the whole world for it and after endless experiments and prototyping that took 2 years - we arrived at a design that sounds better than the original Horizon with the same sound signature that we are famous for. We decided to give the project a green light and we considered it worthy of calling it the new name - Horizon360.
Business-wise, the original plan was just to overcome the parts shortage but as the Taiko Olympus story evolved, we saw a huge opportunity there. Since the Olympus is challenging the status quo of the digital music industry, we joined that process by adopting the Olympus XDMI as the first DAC manufacturer in the world. That is nice, but the market for Olympus is a limited one, by both factors of price as well as their supply output. Therefore we wanted to give to all the people who will NOT HAVE the Taiko Olympus a nice boost in sound quality when the Horizon is used with whatever server / streamer people might have. That means effectively that we put a 2 year research and development effort into improving USB and i2S and S/PDIF or AES/EBU inputs.
The new conversion chip required a completely new, “blank sheet” PCB design, with new inputs, new receiver, new power supply, new grounding, new multiplexing, new firmware and software that controls the conversion process. The main differences (except increased sound quality) are: i2S via HDMI doesn’t need master clock and will work off 3-wire connection - versus typical 4-wire before. That in turns may lead to offering an optional 3xBNC/i2S connection - BY FAR the best digital audio signal connection of the whole hi-fi industry. Better than RJ45, AES/EBU, HDMI, SPDIF, TOSLINK and any other you can name.
DSD now can be configured as 1024x versus 512x before (some of you will be thrilled) however for our internal reasons we decided to keep the maximum at 512x for the foreseeable future. The same goes for
PCM1536kHz sampling rate - the fastest in the industry.
PCM is now set at 768 kHz.
Taiko XDMI interface is now built-in and embedded in the design. Ev
For Taiko Extreme - the sound quality of USB difference will be magnificent. (as well as for the other non-Taiko sources)
The name Horizon360 was suggested by our experience with the first prototype sound: someone commented - WOW, this is like old Horizon only it is a 360 degrees now - meaning - the experience is much more immersive and three-dimensional. It is sort of like the actual horizon when you are on the ocean.
We decided to handle our precious flagship DAC with extreme care and not risk any unnecessary changes just for changes. We left the same tubes, same output circuits, same chassis and display. We wanted to make sure that Horizon remains Horizon and when we are asked - we will answer with confidence that the new one is BETTER not just different and if you liked the H1 - you will love the H360 changes undeniably !
The list of differences versus Horizon-1:
1. New digital engine with new circuit and new parts
2. DSD 1024x vs 512x (not yet enabled)
3. Pcm 1520 vs 760 kHz (not yet enabled)
4. Two i2s ports: HDMI and RJ45 plus a possibility of an optional third “3xBNC” i2S port
5. No need for external clocks signal - a 3-way i2S is all we need now 6. Taiko XDMI link input port built in
7. Improved power transformers - 4 versus 3 before
8. Open path for next 20 years of upgrades
Horizon 1 in its original form will be phased out during the month of August 2024 and the remaining parts will be shelved for the future service needs.
The upgrade service will be offered starting from September 1 and only through the Dealer network.
You can distinguish visually the new version by the front panel logo containing 360 element as well as the rear panel description"
Lukasz Fikus
As for XDMI , it is a completely new interface designed by Taiko and if you do a search here in our search box, you will find Emile's description and by all accounts it merits hearing. I can tell you that I have had my Olympus/IO for 9 days now and my Horizon has the XDMI port and for my ears it is without doubt the best digital sound I have ever heard. If you don't own the Olympus/IO there is no need for your Horizon to be ordered with the XDMI port.
Do a search using our search engine at the top right of the page and search from June 1/2023 through Jan 31/2024 and you will find multiple posts from Emile re XDMI. It is proprietary and thus there is nothing I can share with you but I can also say that I have done a careful comparison using USB from Olympus/IO to Horizon vs XDMI from Olympus/IO to Horizon and the difference to my ears was startling. I have a $15K Masterbult Ultra USB cable that will be sold by me as I just cant listen any more via USB. This is of course one man's story and as the saying goes YMMV