You can also look at it from a general use point of view. Correct me if I am wrong, but the WM1A, 1Z and even the ZX300 are pure music players, right? Whereas some of the others are Android-based with WiFi, App store, streaming, etc., and in that case I would imagine that the average battery life is reduced quickly when making use of those features. To me it would make sense to offer Sony-type battery life on DAPs that have as many features as some phones. But then again, I am not really into that sort of stuff, so perhaps people who use it are also used to constantly charging their gear.
I recently read complaints about Sony not being in tune with modern gadgets, but I think Sony's approach is really sensible. I don't see any need for an app that will allow me to operate my DAP with my phone. That's just me though.
Oh, and another awesome Sony feature that is sorely missed on many others: A proper lock button. I can't fully lock my AK70 and it was the first feature I really missed when I switched. Such a simple thing, but oh so useful.
(Just some thoughts, but I guess it is clear that I have been missing Sony lately.
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