How can I start to change the system?

Osquitar:

Let me start by saying that your written English is excellent -- better, infact, than some of the posts by our members.

There are two sets of opinions about building a system: start with the source components, or start with the speakers. If one has a fairly balanced system (all components of roughly equal quality), I'd upgrade the system in the following order:
1. the speakers;
2. the preamp;
3. the source components;
4. the interconnects and speaker cables.

Of course, if you are happy with your current speakers, then I'd think about replacing your integrated amp as the first step.

One inexpensive improvement might be to go to a purpose built digital interconnet like the Kimber illuminati which can be had used for about $100USD.

Do the room first if you haven't already. What you'd spend many thousands on in components can probably be done for hundreds if you haven't done room treatments yet.
You can mak the system anyway you want with reflective / absorbtive panels and bass traps.

There are two sets of opinions about building a system: start with the source components, or start with the speakers.

And then there's the third set of opinion...

The Psychic says:

Start with power delivery/noise control. The Archives have plenty of information, there's also a power forum in Audio Asylum sponsored by PS Audio ( biased towards their products, of course).

If you would like to find out if what I'm saying is correct, start in this order with some cheap alternatives that will blow you away:

1) Dedicated line for your system.

2) Cryogenically treated power outlet (I use ACME silver plated cryo).

3)Separate power filtration for digital DVD/DAC. Something simple, like a used ONEAC three ampere isolation transformer/filter from e-Bay (around $25 dollars, 15 pounds). Shipping will be outrageous, so surface mail will be necessay.

4) A good power cord for your Rotel, like those from Ven Haus Audio ( Flavor 4 I recommend).

5) Parallel filtration for your entire system.

"Más vale maña que caña."
--Ismael Rivera

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Thanks for your answers. Now I have a better idea about what I can do.

Sdcampbell: My English teacher wouldn't sign your opinion. I just noticed some big mistakes in my first post. :)

Is really important a ground connection?