The following is a list of recommended power supplies for the DB-90;

Boss PSA-120
PSA-120T
PSA-120S

Caution: The use of any other power supply could result in malfunction and/or permanent damage to the product.

Specifications
Product: PSA-120T
Input:
AC 120V 60Hz
9W

Output:
9.6V regulated DC
200 mA
pin [center] = negative