[sdiy] Line Levels in a modular environment

[Altitude]

Hello all,
  I did some testing with my Yusynth filter clone and my WTPA sampler and
have a problem, the signal of the sampler seems to be far too low for the
filter.  I can hear the filter working with everything turned all the way up
but it is VERY low (1/20th of what I would expect and I am running directly
in without a input attenuator).  Some quick reading reveals that modular
components work at considerably higher levels than what I am used to (this
is my first "proper" piece of modular gear).  Will this require some
amplification stage or is there something that can be modified on the filter
itself? The filter has a 100K resistor between the input and the Opamp
before the signal goes to the transistors..
(http://yusynth.net/Modular/Commun/ARPVCF/ARP-4072-sch.jpg)

Tia.

Raph