by the way, there are too many device has line out can be selected. such as Smart phones and PCs.
if paired with the higher quality earphone amplifier, the line out of IPHONE is also very good.
Of course, you will said what you need is the 192K speed, But to be frankly, as portable device, most DAP WHICH claim to provide 192k speed is not really 192k. It is upsampled to be 192 k. It is not benifit to really largely improve the sound quality.
As the digital out signal, 44.1, 44.8 or 96 kHZ sources are good enough. why there are so many audiophiles are not satisfied with it? it is because there are few excellent amplifier to pair with these speeds of music sources. So the audiophiles image to improve the final sound sources by higher speed sources.
Please be aware, CD's sample speed is lower than MP3 files. but the high end CD player is much higher quality than any mp3 players.
This is why we stress that the earphone amplifier is the key or bottle neck on the portable audio system. This is why we say 80 % of the portable earphone amplifier's sound quality is below our standard.
We insist the future of portable audio is not higher and higher sampling speed but the high quality amplifiers and high quality earphones.
for ear is hard to distinguish the difference of 0 and 1 with the speed of 192khz or 44.1; 44.8 ,96 KHZ.
We hope more will chin in to this standpoints. I want to know how many audiophile will support our view point that bassed on current 44.1 khz and 192 khz Sample speed, the key to improve the portable rigs' sound quality is not higher sampling speed, but the excellent amplifiers and earphones.