Thought I would try the easy to do mod of soldering in a couple of 270K resistors inline with the RCA inputs as per Pauls suggested mod in the Crack FAQ section. Using a Vishay 270K, 5%, 0.25W Metal Film and it works a treat.
Resulted in a feeling of having improved range and finer user control of the volume levels it also removed a very slight channel imbalance which was noticeable at the lowest level.
Thanks Paul
Jamie.