Ha ha. Problem with some gods is that they play with us like children picking wings off flies for sport .
Another firmware change in 3 weeks with another sound sig change?
Some people enjoy rolling their op-amp chips - I'm still hoping iBasso will release a DX91 with rollable DAC chips
Until then, I guess we'll have to settle for russian-roulette firmware sound-sig changes
X5 has higher output power but you don't need to max it even on DX90. They both play loud. I use DX90 to drive a 600 ohm headphone and it plays very loud without any hint of clipping.
Do you know the load impedance sensitivity of your earphone? DX90 or X5 should be able to handle it fine.
A comparison I read on a Russian site stated that the DX90 was the better option for driving high impedance cans, apparently the X5 lost its composure when maxing the volume, becoming shrill. While the DX90 keeps its cool even at max volume.
I have both but haven't compared them head to head. What does surprise me about the DX90 is I can max the volume and it doesn't break-up and doesn't show any signs of clipping. I have a feeling that they could have gone with an even higher gain but you really do get everything out of the internal amp without any negatives, IMO.
Technically the DX90 battery has more power output being 3.8v, while X5 battery is 3.7v I believe you meant the X5 battery has a larger capacity being 3700mAH while DX90 is 2100mAH. The battery capacity is unrelated to its power output, its the voltage that correlates to power output, but the difference of 0.1v is not going to change anything lol.
Along the same lines of this daft battery conversation, one could argue that the battery is likely to perform better (and yield more of its charge) if it is kept warm - so that could be used as an argument for a DAP running longer if it runs hotter and thus less efficiently!
Heheh! Well, we don't need to be uber-serious all the time, do we? DAPs are just a hobby.
I'd like to get into Koi carp, too, but these hobbies are always a slippery slope into potential uber-seriousness, geekdom, thousands of dollars being endlessly spent, divorces, etc. etc.
I'm just as guilty as anyone else here, but it's good to remember that it's all just a 1st world 'problem' and, for the most part, a battery is best viewed as just a battery, and maybe we should lighten-up and just have some fun/enjoyment every once in a while