If the hardware has a different designation number, then the difference between them, in nearly all cases is ‘everything’. That is, the base board we used before the customisation completed for us by the original manufacturer, and the customisation we do, is a completely different board. This is not the case every time. Sometimes the change is only in the version of the board, where that change makes a very significant change to the sound quality.
A change log would be meaningless, unless that log said ‘everything’ in most of the lines.
We have a deliberate policy of not talking tech details because we see no value for a buyer in trying to discern what must be best based on a list of specs. We will make no apologies about that either. Live by that sword and you die by that sword and you get pushed, like so many DAC manufacturers have been, into changing their products just so that they can add the next tech acronym into their blurb. We will live or die by our sound quality and side-step that bollocks.
We will talk about tech insights, and we do. But not meaningless tech detail. If you really think pouring over the tech detail will tell you which sounds best then fill your boots but we won’t participate in that.
As far as our designations are concerned, they are there to say that something has changed significantly. Bigger numbers mean later/better, H means high power optimised for Server apps, and X means medium power optimised for Player apps. And please read that last sentence carefully. It does not mean you should contemplate using an X for running just the server app (using an undemanding app) and another for the player app . This misunderstands three things.
All server apps require high power to perform the server function, irrespective of the server app used.
This will sound terrible due to intermodulation effects. A single X will sound better.
We do mean it when we say the modules are optimised for a task.
The R2i reclocker is indeed still the R2i reclocker.
The changes we made to the revised K50 involved new power supplies, new player board (looking at it you might not think so, but it is very different). But it drives me nuts that people think this is a computer and it is just parts that change. The parts changes in the revised K50 means that everything about the customisation and optimisation had to be re-done. This iS by far the biggest influencer of how Antipodes music servers sound.
Of course the USB changed - the Player board changed, and it has also changed in the Oladra.
It would be useful to check out the archetecture page Solution Architecture - antipodes to properly understand USB versus Digital Outputs. If you choose to use USB then your DAC had better have a very good reclocker (after the USB input, not before it), and many don’t. Instead they typically rely on the much cheaper asynchronous oversampling or conversion to DSD, which is more of a trade-off than it is an improvement.