The DIP is a "digital interface processor" (I think that's right), manufactured by Monarchy. It's a jitter reducer to be placed between the transport and dac.
Since the DIP is designed to reduce the jitter introduced by your transport, I would have imagined that its effectiveness in a given system was determined by the characteristics of the transport, not the DAC. For example, I used to use one when my transport was a Rotel multi disc player, and it passed the digital signal on the a modified DIO. In this situation, the DIP had a significant effect. And I suspect it would have continued to have a significant effect if I had been using a completely different DAC. But if my transport had produced lower jitter levels, the DIP would have provided less impact.
If arthurs found that the DIP had little or no effect, then this should be a reflection of low jitter coming from the transport. For somebody else, using a different transport, the effects of using the DIP prior to the same DAC might be significantly greater.
Having said that, I would guess that the SB3 is a pretty low jitter-producing transport. So it would seem unlikely that Charles would get much from using a DIP.