Originally Posted by Mimouille
What does change in mw entail?
I'm not an electronics engineer. My understanding is simply that an amp capable of delivering greater current will handle low-impedance loads more adeptly. It is very important to understand that headphones do not have 'an' impedance rating. Their impedance varies with frequency. This seems to be a particular issue with some of the multi-BA CIEMs, which, at certain frequencies, can present a remarkably low impedance to the amp stage. Crudely-speaking, lower impedances draw more current from the amp stage, so (again, crudely-speaking) if the amp stage 'runs out of steam' it may not be able to drive the armature / diaphragm cleanly to it's intended excursion for the piece of music being played.
As just one example, my Cowon J3 failed miserably to adequately drive my UM Miracles (which, as you know, is a 6 BA per earpiece design). The treble was coarse and splashy, and the bass was woefully inadequate. I would never have believed how much of a difference the DX100 could make to the sound of the Miracles until I heard it for myself. I don't mean in terms of the DAC or anything, I mean in terms of the interaction between the amp and the CIEM. It was a major eye-opener for me and one I will never forget. So profound was the difference that I literally went from considering a change from the Miracle to the Merlin, to suddenly realising that the Miracle DOES have decent bass response, when driven appropriately. For comparison, the J3 has quite respectable bass response with dynamic drivers such as my Denon AH-C701. I admit I did rant too rather too much in the X5 thread, when James announced that the power output was to be reduced. Whilst I appreciate that the X5 will be more powerful than the J3, it was nonetheless because I have experienced how drastically the SQ can alter, depending on how capable the amp stage is, that I was so disappointed at the reduction in spec of the amp stage of the X5.
This is complicated, of course, by differences between DAPs in terms of their amp stage's inherent output impedance. And I know you already know all this; we're just chatting here
We will have to wait and see if Sony have spoiled all their hard work by producing the ZX1 with insufficiently-low output impedance. Now, this is something I would welcome any of you electronics whizzes teaching me about - with a Class-D amp, am I right in thinking that output impedance is a rather different kettle of fish? I hold my hands up and openly admit that I lack electronics expertise, so I welcome anyone educating me on this issue.
This ZX1 is looking so exceptionally sweet, in terms of design and form factor, that I might be willing to make an exception and consider using it with a seperate amp. I have always steadfastly refused to consider a seperate amp, but with something so compact as the ZX1, I might just make an exception...