Question

On the DP88, can I use the Direct to Converter Line Inputs (DB25 connector) for 4 external mic pres and still use the DP88's internal XLR connectors to utilize the preamps for the remaining 4 channels?

Answer 1

From page 3 of the DP88 User Manual: 

The DigiMax DP88 provides direct-to-converter line inputs for every channel via a DB25 connector on the rear panel. Press this button to enable the Direct input for the currently selected channel.

You can choose the source on a per-channel basis using the Direct button on the selected channel to choose the line input.