Got lucky really, did a search on Hi Fi Shark, messaged a chap from a Hi Fi forum in the Netherlands, and sorted it via email.
Hi Fi shark is quite good for tracking stuff down, providing you can work with the seller to ship abroad.

Damien

Patience is a virtue
Everything comes up eventually sometimes at a daft price
Worth messaging the seller to ask if they will ship abroad even if they state categorically they won't

If they are willing to sell, you could always arrange the courier Brett? Takes the hassle off their hands.

Shouldn't be that much, my AD clock ,PSU ,2 leads and adapter was only just over 2kg in weight

Hello chaps, I now have the U18 up and running.  

Initial findings are certainly promising but want to check Volumio settings if anyone can advise.

In the Volume Settings I have U18 Hardware selected - I presume this is best?

Cheers.

I am posting my initial thoughts on my blog.

Is that just when using with a PC, Martin?

Now that I have lived with the Gustard U18 DDC for a while, what does it, and I2S, bring to the party?

The most obvious change is how it throws highly focused vocals and lead instruments stage front and forwards, while layering the soundstage behind it back to the far depths and corners. The stage is simply wider and deeper than before. Not only that, but instruments are better separated throughout the width and depth of the soundstage. Further still, the dynamics of each strand of the music brings out every tiny detail in the performance, sometimes quite startlingly so.

This is where I hear the benefits of a DDC like never before, and how I see that combo of DDC and DAC to be truly symbiotic. Of course, external clocks, power arrangements, footers & weights and such further benefit it but the move from AES to I2S was a very significant one and not something I could do without.

It has been a significant step up in performance for my system and a surprisingly inexpensive one at that.

An observation: I am temporarily without my U18 while it is being upgraded. I have connected the Rendu direct into the X26 Pro's USB input and connected the master clock to the DAC, too.

Upon initial listening, it sounded pretty reasonable. However, further listening reveals a slight roughness. Treble is slightly accentuated, bass potency is slightly down. Listening intently just now, it's not holding me riveted to the music as before.

There is a sense of vividness, rhythm and attention-holding magic that the U18 and its reclocked conversion to I2S imparts to music. This is what I first heard when John and I tried his U18 in my system and the magic is still there in what it does to the music. A nice validation of the U18's place in my system.