It's interesting that you've noticed this lag - I would assume all AK players, from the 100 II series and up, are operating lag-free. I've owned an AK120 II in the past, and the UI was as smooth as butter. I'd assume the AK300, a newer model, would fare similarly well.I wouldn't say that the AK70 lags at all, I have no problem with it. It just seems like the AK300 is less responsive. It's not a deal breaker, but it's noticeable to me. I was a little curious if all the other specs on the AK380 was the same as the AK300 (asides from the DAC) such as the CPU.
And it's reassuring to hear it wasn't just me having trouble with the metal touch button.
In any case, I'm glad to see that AK have abandoned the metal sensor on their newer players (SP1000, KANN).