Originally Posted by mfst23
Till today, there are only 3 dap models to choose from which has high power output which are suitable to drive demanding headphones. With the small form factor and high power amp, all the current models playback time are very short and none cannot even reach 20 hours. It may looked like it is a lot but in reality as the battery capacity degrades over time, it becomes a chore having to charge it almost everyday for heavy users.
Not just Ibasso, but Fiio is coming out with the X1 was designed with lower power output and for driving IEMs, however, such a design won't mean that much longer battery life, only a smaller form factor similar to an iPod Mini, but basically the people excited for this are those who want something more powerful than a Sansa Clip, but is still relatively cheap at $99 compared to other non-integrated audio chip DAPs.
In any case, didn't Ibasso already deal with battery life by using the Samsung S3 battery on the DX50? I'm actually considering getting a a used DX50 instead of the X1 if I find one cheap - I have three spare batteries on my S3 and also a battery charger (like a camera battery charger - you put in a battery instead of hooking up the phone to its USB port), since I can always just put the DX50 in my messenger (laptop) bag and use the phone if I don't have one with me.
Now, I know neither addresses your needs for a smaller DAP with longer battery life, but you have to be realistic here. A smaller form factor will likely mean a smaller battery, and you can't compare such DAPs to more mainstream designs like Cowon. Cowon, Apple, Samsung, most Sony, etc all use a single audio chip that has both the DAC, digitally-controlled voume control, and headphone driver chip built into it; by contrast, Ibasso, Fiio, etc use a dedicated DAC, analog output opamps, and an actual power amplifier circuit with capacitors that are closer to the size that you'd find in a dedicated amplifier. Making a 30mW DAP isn't impossible, but given they're already using an amp circuit that will take up that much more space, it makes more sense for them to squeeze out at the very least, around 100mW minimum and get a wider range of IEMs and headphones that can work with it, even if it is a smaller form factor.
Think of it this way (in terms of the audio circuits, not their CPUs and responsiveness) : the first group of DAPs/smartphones are more like an ultrabook with a low-voltage Intel i5 running its own integrated GPU, while the second group is a lot more like a gaming laptop with an Intel Core i7 (and some laptops might even use a desktop version) and a GT865M. There will be two problems in designing something between these two however. First, as I've stated above, having a dedicated graphics chip or a dedicated DAC, output op-amp, and amp chip will mean occupying the same amount of space in a chassis (don't factor in something like the GTX760 ITX vs the Titan though), and 30mW isn't that far off the 15mW output of the best integrated chips save for better current. In laptop terms it will be like getting a ULV i7 mated to soemthing like a GT750M, except that kind of laptop actually has a much wider market - people who would want to be able to edit photos and videos, and maybe do some lighter gaming on it. The second problem is that, unlike laptops, there isn't yet an integrated chip that is a lot more like a Trinity (heck even a Llano) APU, on top of which, I'm not sure if in case an audio chip does come out as such, if it can work with some larger caps outside of that chip to help the amp section, or if there's a way to circumvent using that and still provide better current than an integrated chip.
Or actually there is a way that a DAPs circuit can be reduced in size, and that is to eliminate the need for an analog output stage and potentiometer (the latter was eliminated in the DX50), and use a circuit similar to the Wadia 151 Power DAC where the DAC chip directly feeds the amp output stage. However, it relies on an upsampling circuit to take the digital signal to 32bits, that way the digital volume control doesn't dip below 16bit. One can argue that you can go as low as 14bit or even 12bit, but the problem is that it is very likely that the type of people who will buy such DAPs will not be happy about that, regardless of whether the actual sound has any audible degradation, while people who don't even know that music is at 16bits (much less that 20bit, 24bit, and 32bit are available) will likely not be swayed into buying a DAP with buttons to occupy a pocket and perform a role that their carrier-subsidized touch screen phone already does.