where do I connect the earth in my pre to?

My Lamm LL2 has an earth connection in the back, and a 3-prong power cord. I asked Lamm where was I supposed to connect the earth to, and the answer was not to worry about it - the earth connection is for US electrical systems only (I'm in Argentina). Yet I wonder what makes the US electrical systems different, and was wondering if I'm missing something by not having this connected.

So here goes my question: where should I connect this to? And what benefits could I expect?

Thank you!
Most preamps have a ground connection used primarily for a phonograph grounding point (Most turntables need a grounding wire to the device the cables are connected to or will have a strong hum result. Separate phono preamps also have a ground connection, and can be grounded to a preamp to reduce hum. (but often not needed.)
So the comment from Lamm was correct.
As for the three prong power plug. If your country does not have a ground in the AC system, then best to ignore the ground pin.
IF you MUST have a ground, the way to build one is to get a solid copper rod ten feet long and drive it into the ground with just the top sticking out. (assuming the ground is dirt) Connect any ground wires to the grounded rod. (if you have stone, sand or dry material for the outside earth, then you should look up the way to connect a ground rod via Google.
You mostly would have a tiny bit more electrical safety with a ground installed. It may or may not improve or injure the quality of your system performance... Being a bit of hum one way or the other. If your system is pretty quiet with no music playing, a ground is not going to help much music wise.
Hope this helps!
It is unsafe to "ignore ground pin". Gear with two prong plug is designed differently.
sorry, maybe I wasn't clear enough. Our local code also makes a ground mandatory, and my home has a pretty good ground (had a new one installed before moving in).

My comment about the ground pointed to why a ground and an earth connection? Lamm pres don't have built in phono stages, so why the earth?
I don't doubt the comment from Lamm is correct! Just wondering where I should connect the earth to. Water pipe? Anywhere? Ground in my power line?
If you are talking about a ground lug or thumbscrew on the back panel, that IS for a phono stage, and does not need to be connected to anything except a phono preamp.
Do NOT connect it to any water pipe!!! or other ground. It is to ground another bit of gear, NOT the preamp!
The idea of a grond rod was ONLY for the electrical AC plug IF you did not have a AC ground.
Elizabeth is mostly correct, but not comopletely. It is common for preamps (and other components) to have this ground "lug", even in a unit without a phono preamp. The purpose is to ground various pieces of equipment to a common component to address ground loop issues.

However, that being said, my suggestion is similar to hers. If your system is hooked up/connected and you are not experiencing a ground loop, then ignore it/don't bother connecting your components via this ground lug. However, at some point if you do experience a GL, then you can use it to possibly address a GL problem.

Not connecting anything to this lug is not going to cause a problem in and of itself. It is a conveniece feature that can be used for the above referenced problems (in addition to other grounding schemes).
In some countries the term "earth" is used to mean the same thing that the term "ground" refers to in the USA, which in this case would mean chassis ground/circuit ground/ac safety ground (all of which are usually connected together in audio components that have three-prong power plugs).

So what is labelled "earth" on your preamp is just the ground thumbscrew the others have referred to, that is usually provided on preamps. It should not be connected to the physical Earth.

Some countries, including among others Russia and some parts of Argentina, according to this Worldwide Voltage Guide, appear to have only two-prong ac outlets. That would reduce or perhaps eliminate the potential for ground-loop problems, which is probably what was behind the comment that "the earth connection is for US electrical systems only."

-- Al
OK, thanks for the feedback.

Al: that website is outdated. 3-prong installations are mandatory here. Also, it's not me using the term "earth"; it is printed on the back of the Lamm, which is a unit initially meant to be sold in the US.

I guess I'll forget about it: I don't experience any ground loops, no hum or hiss, except a little hiss I can hear with my ear to the tweeter and the volume wide open.
And I have no vinyl.

Thanks all for the input!
It's not me using the term "earth"; it is printed on the back of the Lamm, which is a unit initially meant to be sold in the US.
Yes, I understand. Note that I referred to "what is labelled 'earth' on your preamp." I had looked at a photo of the rear panel of the LL2 prior to submitting my post.

What I was implying is that since the term "earth" is used in some non-USA countries to mean the same thing that the term "ground" is used to mean in the USA, and since the preamp was designed by someone whose native country was not the USA, the "earth" designation was most likely intended to mean "ground," not the physical "Earth."

-- Al
A further note FWIW: unless your home's electrical system is sorely in need of update, there is no need to pound a stake in the yard for an electrical ground. The ground prong of the AC cord should go to the house's central AC ground, which in turn is usually connected to a cold water pipe.

You can have a different potential with a ground stake, which may well vary with water content in the soil. All that is is a recipe for trouble- the house ground is the only thing that matters.

Now audio gear in general does not like to be grounded but in order to sell it legally, it has to be grounded. You will find that various manufacturers are at various stages of development in this regard- some will have grounding schemes in their equipment that work flawlessly. Others will have outright errors that can introduce ground loops and still others will not be grounded at all.

So there is a big IF that is going on here. IF the equipment is built correctly, there will be no benefit whatsoever from any additional grounding beyond that of the AC wall ground. IF the equipment has bugs in it, then *maybe* a stake in the yard might help, but IMO and IME the stake in the yard solution is not only inconvenient, its asking for trouble. Its best to sort out what the bug in the gear is, even if that means getting the manufacturer to find a proper solution.