What Powder is describing sounds like normal (and what I would recommend) grounding to earth ground. Clio, your question was regarding floating ground and the bypass cap will work and still maintain a floating ground.
But as everyone on this thread agrees, good grounding is essential to shunt any RFI energy away from your system. The shield on your cables and the metal around your components will shield them from RFI BUT (and it's a big BUT) you have to move that RF energy away from your system or it will find another way in.
The way electricity works is it flows down the path of least resistance. So you need to provide a super-highway for the RF energy to travel on that moves it away from your system. If you do, you'll never hear the RFI. That is one of the main purposes of grounding. RFI has some other characteristics that we can use to whisk it away. Without going into the details it's to use wide and flat grounding straps and bypass capacitors to "widen" the super-highway for RF energy. We can also use ferrite beads to absorb the RF energy before it enters your system.
So far, this the only money we've spent is probably $20 for flat/wide copper braid ground straps and $1 on bypass caps. Connect the braid to each of your components keeping the lengths as short as possible (use a "star shaped" configuration). Then run some braid from the center of the star to earth ground (the roundish hole in your electrical wall socket). You should also buy some ferrite beads and put these around your power cord and each end of your interconnects. This will add another $15 to your bill. A final remedy for RFI is shielding. Not in the cable, but shielding the entire component from either radiating or receiving RFI. You can do this with heavy aluminum foil and some of that flat/wide copper braid (ie the aluminum foil has to be grounded to be an effective shield).
Now assuming your interconnects aren't completely horrible (they must be shielded if you are having RFI problems) your system will be properly grounded. It will sound like it's on steroids with incredible inky blackness and the notes appearing in space out of nowhere with no hum or hiss and holographic realism that will rival the big buck systems! WOW! INCREDIBLE!
As a final note, I'll add that most people do not have either RFI or EMI problems. Only those who live near a radio tower or some other structure/device that generates RF. This is why most people can just use regular wire and not flat/wide copper braid to ground their systems and get WOW fantastic inky black backgrounds for $3 instead of $35 (most people don't need the bypass caps or the ferrite beads either). But they don't hurt and they are inexpensive so better safe than sorry.
I think that covers it... did I leave out anything? Probably, but these are the basics of the simple, inexpensive, things anyone can do to properly shield their system from RFI. There are a few more things for extreme cases and EMI like BALUNs and chokes, but these are inexpensive, too.
So take some time to learn and implement these basics yourself. Or buy a beautiful box for almost ten thousand dollars and more cables at three grand per meter. Another option is to hire an electrician to come out and properly ground your system. That will probably cost you a few hundred dollars, but you'll know it's done correctly. I can describe the science, but the art and pride of ownership is certainly worth something. How much is your choice.
But as everyone on this thread agrees, good grounding is essential to shunt any RFI energy away from your system. The shield on your cables and the metal around your components will shield them from RFI BUT (and it's a big BUT) you have to move that RF energy away from your system or it will find another way in.
The way electricity works is it flows down the path of least resistance. So you need to provide a super-highway for the RF energy to travel on that moves it away from your system. If you do, you'll never hear the RFI. That is one of the main purposes of grounding. RFI has some other characteristics that we can use to whisk it away. Without going into the details it's to use wide and flat grounding straps and bypass capacitors to "widen" the super-highway for RF energy. We can also use ferrite beads to absorb the RF energy before it enters your system.
So far, this the only money we've spent is probably $20 for flat/wide copper braid ground straps and $1 on bypass caps. Connect the braid to each of your components keeping the lengths as short as possible (use a "star shaped" configuration). Then run some braid from the center of the star to earth ground (the roundish hole in your electrical wall socket). You should also buy some ferrite beads and put these around your power cord and each end of your interconnects. This will add another $15 to your bill. A final remedy for RFI is shielding. Not in the cable, but shielding the entire component from either radiating or receiving RFI. You can do this with heavy aluminum foil and some of that flat/wide copper braid (ie the aluminum foil has to be grounded to be an effective shield).
Now assuming your interconnects aren't completely horrible (they must be shielded if you are having RFI problems) your system will be properly grounded. It will sound like it's on steroids with incredible inky blackness and the notes appearing in space out of nowhere with no hum or hiss and holographic realism that will rival the big buck systems! WOW! INCREDIBLE!
As a final note, I'll add that most people do not have either RFI or EMI problems. Only those who live near a radio tower or some other structure/device that generates RF. This is why most people can just use regular wire and not flat/wide copper braid to ground their systems and get WOW fantastic inky black backgrounds for $3 instead of $35 (most people don't need the bypass caps or the ferrite beads either). But they don't hurt and they are inexpensive so better safe than sorry.
I think that covers it... did I leave out anything? Probably, but these are the basics of the simple, inexpensive, things anyone can do to properly shield their system from RFI. There are a few more things for extreme cases and EMI like BALUNs and chokes, but these are inexpensive, too.
So take some time to learn and implement these basics yourself. Or buy a beautiful box for almost ten thousand dollars and more cables at three grand per meter. Another option is to hire an electrician to come out and properly ground your system. That will probably cost you a few hundred dollars, but you'll know it's done correctly. I can describe the science, but the art and pride of ownership is certainly worth something. How much is your choice.