Do you actually have a DC problem? Can you identify the source and remove it?
If you turn off everything else in your house and you still have DC it's time to call the power company.
I'm using a Long dog audio one inline to my power conditioner. it makes a positive effect in my opinion in my system but it does limit my power cord to 12 gauge.
my issue is a fish tank with variable DC pumps and variable LED lights.
one day I'm going to try blocking the DC at source (other side of the room)
Then taking it out of the system, I get no hum on my transformers without but I find the tone sweeter with it.
@holmz I don't necessarily have a problem. Don't know if I have a problem or the equipment to test if I do. Was more a general question after viewing reviews of DC blocker products and the positive affect for minimal investment.
@tunehead - Avoid them unless you have an issue. One more piece of gear to break.
DC should almost never happen in a home, and usually it's caused by things like LED power supplies and dimmer switches. Usually best to deal with the source of the problem and only if that can't be dealt with due to WAF and budget or being a tenant then a DC blocker is in order.
A better idea IMHO is to monitor your AC voltage near your rack and see how much it varies. If you see too much a voltage regulator may be a good idea.