and for ClieOS, Jiushao E300 v E600 which one will you prefer?
#from the SQ not the price
Won't say one of obviously better than the other. For mainstream music, I'll pick E300. For instrument and Classical, probably E600.
The worst option for that sir?
Add $9 more to your $50 budget and you can get Etymotic MK5, which is about as reference flat as it can be under $100. But it is an IEM, not an earbud. To mix with earbuds, or with any kind of headphone, you need to beware not to over compensate. The point is to understand what you listen on headphone will not be the same as on loudspeaker.