This depends on which 25 pin (aka DB25) connector you are going to be using. There are 4 on the back of the DP88
- Line In
- Mic In
- Direct Out
- D/A Out
It all depends on what you're going to be doing. If you are doing synthesizer music, and you don't need the XLR's, then you'll need a 25 Pin DB25 to TRS Snake. If you are doing mostly vocals, (like a choir?) and you need all Mic Inputs, then you'll need a 25 Pin to XLR-Male Cable.
Not sure why you'd need the ART P-16 if you need more line inputs, then just use a 25-Pin DB25 to TRS Snake and then enabled Direct On each channel so the Mic Pre is bypassed for the Line Inputs.
You can download the manual from our website here: http://www.presonus.com/products/DigiMax-DP88/downloads
Read the manual from front to back, then decide your setup and purchase what you need. Contact the guys at Sweetwater, they'll help you make the right decision and select the right cables for your rig.