I have always been wondering whether I would hear a difference in sound between a good DAP ( I like the AK70) and my mobile phone Mi Note Pro which has a internal DAC and separate amp for hi-res music. If it is just a placebo effect, then I prefer not to waste my money. Some even say that I have to have a very good headphone to hear a difference. That becomes a huge investment. Is it really worth it?Which in-ear headphones would be sufficiently good to hear this difference?