Tested the 880 and 990 32ohms and the T70p .The shop doesn't have the 250 or the 600 ohm variants.
Overall the 880 and 990 sounds pretty similar. The 880 sounds more neutral and detailed. The 990 bass is just there with a lot of oomph and presence and also sounds much fuller compare to the other 2.
The T70p to me is too bright but very detailed as compared to 880.
In this sense, the 990 is the one for me. But I'm scratching my head now if I were to get the 600 or 250 of the 990. I'm running on o2/odac .