I have NO way of listening to headphones before I purchase them due to living outside any major city. I'd like to have some advise on this. I recently purchased a set of Grado SR80e that I really like. I'm listening to them on a iBasso DX-50. With that being said, which would be more my range: the 880 or 990? I'm sure that the DX-50s amp will push the 600 ohm as well but should I just get the 250ohm to be sure? Any advice will be most appreciated!