Output loss would be just under 6db due to the output impedance. Others have said that senhiesers like low output impedance. I don't have any Senhiesers to test how well they work with high output impedances. The ones I listed are the Etymotic research ER4P & Shures best sigle driver IEM. I cannot speak for other nor endorse something that I have no experience with. I have had experience with other dynamics that did not seem to care about the output impedance but others may be sensitive. I have no wish to make a blind generalization here of what will work outside of what I already listed that is known to work properly.
Edited by germanium - 1/20/12 at 9:28pm