Greetings all. I was in the DUC forum when I came across this.

Upgrading Sound System
One of the most common questions on the DUC is about adding external preamps and AD/DA converters. This section is for clearing up any confusion about adding external preamps and converters. The Digi 001 pres/converters are good for the money and home recording hobbyist, but to get to a pro level sound I suggest you upgrade them both. This will also add to the number of I/O you can use up to 18. You can bypass the Digi converter by using an external AD/DA converter via SPDIF or ADAT lightpipe. So your prechain would look like this:
Mic>Preamp>Converter>SPDIF or ADAT Lightpipe>Digi 001 or 002 I/O box>PTLE
Some preamps also come with converters built in.

I am using the 002 and was just getting ready to buy the toft atc-2 channel strip along with the RODE k2. My question is will i also have to buy a converter? And if so what is the converter for? And what is the SPDIF or ADAT Lightpipe for?
I thank you greatly for any replies!