Pablo, looking back at my DL103 that is sitting in my RB600 Rega arm, the
Denon is slightly longer than the Kontrapunkt A I have. However it is sitting
much more to the front of the headshell so that effectively it does not extend
further into the back than the Kontrapunkt. It might be possible that in order
to achieve the correct geometry (using a DB protractor) the cartridge has to
sit more forward in the headshell, so that there is no problem with the
hookup pins hitting the tonearm pins on the Ekos as well. Did your dealer
check the alignment correctly?
TWL is probably right in that the Shelter is a better cartridge anyway (still
hoping to hear it someday). Can't argue with him. However the size/length of
the cartridge won't tell you very much wether it will extend to far to the back,
since that will depend also on the cartridge alignment to achieve the correct
geometry. It might be worth trying to shift the arm slightly forward so that
the cartridge can be mounted as far up front as possible.
Also I do remember seeing people use the DL103 with an Akito or Ittok arm,
can't remember the websites though.
Again, Good Luck!