Ako rin nalilito since the UK3II looks the same and different to both the A400 and A400X. And it's also rare, you don't find it in most Jap hifi directories, kahit sa auction market. My hunch is that after the a400X, the Japs went back to a simple A400-based amp that was never sold in UK. That amp became the limited edition UK3II with "Simple and Straight" circuitry. The headphone jack and the bi-wire speaker terminals were removed. If you look at the front panel and the innards, nothing much changed, however.
By the way the domestic version of the A400 or A400X (A-UK3) didn't sell well in Japan as per auction records, roughly 10,000 yen used. I think that reflects the difference in sonic preference of whites and oriental ears and their listening environments. They use heavy bricks in cold and quiet UK homes, while we use lighter materials in our warm and, sometimes, noisy rooms due to airconditioners. That makes a significant difference in my opinion.
Here again is my unit:
