This used item is located at 

Music Go Round Boston location: 

810 Worcester St Natick MA 01760

Tested and functioning.

From Soundtown:
"With the SR400D room delay, dialing-in the unique sounds and characteristics of each venue is a breeze. The SR400D lets you enter in information such as Delay time, Room temperature and humidity and then it takes care of all of the calculations for optimizing the sound of the room. The SR400D provides you with single or dual input and output configurations, with two independent, programmable delays. The SR400D also comes equipped with XLR and Barrier strip Inputs and Outputs as standard features."

With questions, ask for Marcus!