DA-5L Grounding Techniques
The DA-5L contains a switching power supply that will add an audible hum to your audio signal if the unit is not plugged into a properly grounded three-pin AC socket. Unless you’re using a “star ground network” (see below), you must not use an adapter to lift the ground from the DA-5L AC cable.
If the DA-5L is correctly connected to a grounded three pin socket and you still experience hum or buzz when using it with other audio devices, there's a simple test to determine the source of the problem: with all devices powered on and connected with audio cabling, physically remove each device, one by one, from the rack. If the hum disappears when a particular device is removed, you'll know that that device is the culprit. If the offending device uses a two-prong plug (or an external two-prong AC/DC adapter), you can try reversing the plug in the socket. If that doesn’t work, you may need to physically ground that device’s chassis by connecting a wire (called a strap) from it to a grounded piece of metal such as rack ears. Some pieces of equipment have a screw- type ground post to which the strap can be connected; if not, you can attach some kind of metallic binding post to the case itself.
In addition, you can minimize possible interference by planning your RF antenna, audio, electrical, and computer cable runs so that they are as far apart from one another as possible and so they don’t run parallel to one another. If they have to cross, try to ensure that they do so at a 90° angle (that is, perpendicular to one another). In particular, try to keep audio cabling away from external AC/DC adapters
If you’re using the DA-5L in a fixed installation, you may want to invest the time and money into creating a star ground network for all your audio devices. This is by far the best technique for avoiding grounding problems. It involves using a formidable ground source such as a cold water pipe or a copper spike driven into the earth. A thick grounding cable is connected to that source and is then brought to a central distrib- ution point; from there, individual cables are connected to each piece of equipment. This setup also requires that you lift the ground plug of all three-prong AC connectors, so there is the possibility of danger if it is done incorrectly. We strongly recommend that you contract with a qualified professional to carry out this or any kind of electrical work.