Is grounding with RCA is safe?

I see. Thank you all for your inputs. 

I searched online and learn that ground loops can destroy audio gears in long run. Is it true?

I still have a question regarding your reply: 
"In effect what you are most likely doing (depending on the designs of the components) is connecting the internal circuit ground of each component to the chassis of that component and to the chassis of every other component in the system"

I check the ground box from Entreq. It looks like to me that they do the same thing.

Could you help shed some light on this?

I have to apologize for my ignorant questions because I am a dumb in electricial area.

Thank you.

I still have a question regarding your reply:
"In effect what you are most likely doing (depending on the designs of the components) is connecting the internal circuit ground of each component to the chassis of that component and to the chassis of every other component in the system"

I check the ground box from Entreq. It looks like to me that they do the same thing.

Could you help shed some light on this?

The internal circuit grounds of most components are connected to the ground sleeve of their RCA connectors. And since the components apparently have three-prong power plugs, the safety ground prong on those plugs is presumably connected to the chassis of the corresponding component.

So since you have connected the ground sleeve of an RCA connector to the safety ground pin on the power plug of each component, and the safety grounds of all of the components are connected together via the outlets and the associated AC wiring, you have most likely connected both the circuit grounds and the chassis of all of the components together.

I have no knowledge of Entreq products, but if in fact they do the same thing I personally would not want to use them.

I searched online and learn that ground loops can destroy audio gears in long run. Is it true?

I can’t envision a means by which a ground loop could cause damage, other than in the very unlikely scenario I described in my previous post. A ground loop could, of course, have adverse sonic consequences, and degrade the accuracy of the system. Which may or may not be subjectively preferable, however.

Regards,
-- Al

I wouldn't say it is unsafe, per se, but many designers deliberately lift the ground to prevent noise issues. Seeing a 100 Ohm resistor between the chasis, which is directly attached to the AC ground, and the signal ground is quite common. 
The quietest systems I've ever heard completely isolated the signal ground from the AC ground, preventing ground loops altogether.

I would not encourage anyone to start hacking this way.

In most components the circuit ground is directly connected to the chassis. And the chassis is connected to power cord ground. Pretty sure all common ground amplifiers are set up that way. You would not want to try your RCA trick with a non common ground amp.

So what you are proposing technically not make any difference, but anything goes with audio. According to the books what you are doing should make the system sound worse. You are supposed to ground everything in a component to a single point on the chassis via a "star ground". Grounding to different points is supposed to do bad things to the sound.

I would take a peek inside and make sure the circuit ground is connected to the chassis somewhere. The power cord ground should be connected to the same point. Then even though it goes against conventional wisdom......if your system sounds better go for it.

In most components the circuit ground is directly connected to the chassis.

I believe that is not true. And certainly, IMO, a **good** design will not connect circuit ground and chassis directly together, as it invites ground loop issues.

As Erik indicated, many designs have a resistor connected between circuit ground and chassis, and many others go even further in isolating them from each other. I know, for example, that circuit ground and chassis are not connected together in most or all Audio Research, Ayre, and Atma-Sphere designs, among others.

Regards,
-- Al