Yep, everything I've found so far: The DA3 won't run on most smartphones.
The SMSL X4 should have the lowest power consumption, the IDEA has higher power consumption than X4 but should work with most smartphones (no idea if this also applies to iPhone).
The SMSL X4 should have the lowest power consumption, the IDEA has higher power consumption than X4 but should work with most smartphones (no idea if this also applies to iPhone).