Sennheiser matched with a DVR Olympus DS-40

["Bruce Tannehill" tannehill]

My principle recording interest is bird vocalization.  I often use
Raven or Syrinx sonogram software to compare differents between
individuals of the same species.

I have a Sennheiser ME 66 with a K 6 powering module.  I have used it
with a Sony MZ-R37 with moderately good results.  The principle
problem being the time to down load the sound files in real time, cut
them up into sepperate files and keep comments on the files.  Recently
I have started to use a Olympus DS-40 Digital voice recorder.  The big
advantages are that I can carry it with me everywhere, it has a high
recording level (compared to other DVRs) and I can download via USB. 
I have tried using the DS-40 with the Sennheiser.  This gives me great
volume but an unacceptably high noise level.  My question is, is this
an impendance problem?  The Sennheiser lists 200 ohms balanced and the
DS-40 lists 680 ohms.  If it is an impedance problem, how do I solve it?

Bruce