Most the time, balanced sources will drive an unbalanced input with no problems. In some rare situations, a mic pre or small board will not like an unbalanced load being presented to them but most of the time, this is not a problem. Cables to transition you from TRS or XLR balanced to RCAs are available at almost any Guitar Center.

The issue is the levels more often. Balanced is usall a nominal +4 signal while unbablanced RCA inputs are usually at -10 or worse, -20dB. It is very easy to overdrive the inputs of a receiver with a +4 board. Be sure to use caution. A worst case scenario would require you to get a level matching amp or a transformer based step down like those from Ebtech to make the proper connection.

If I got it right my amp in a bad case might be overwhelmed by the signal?
And what is a +4 board?
The effect of this configuration will be at least worst sound coming from the monitors I suppose?
Sorry for the many questions but... lack of knowledge

+4dBu nominal output

yes this will be a great deal of level for the average home Technics amp.

a simple solution is to attenuate the signal from the desk ... near the input of the amp.
As Kurt 8-) has said above ...
but I'd prefer to see you use a resistor based idea rather than a transformer as it is likely you don't want to spend the money require for a quality trafo ... this is your main monitoring so lets keep it as clean as possible.

although not finished yet ... let me sneak a little of my new web pages your way.
http://www.diyfactory.com/projects/dawmonswitch/dawmonswitch_1.htm

one of the important things to do, is get each bit of gear working at a signal level it was designed for.
people refer to this as ... Gain Structure

In essence it is when the desk is working correctly and the meters and signal to noise is all in spec ...
and
your home amp has the volume at around 10 or 11 o'clock
the overall volume should be quite strong and near clipping of the Hi Fi amp.
can explain more and why later.
This is where the trimmable pad at the front of the amp will be set.

does this make some sense ?

Ok...I think I got the most of them... The route will be guitar (unbal)-> guitar multi-effects processor (unbal)- console(bal) - soundcard(bal) -console(bal-unbal) - amp (unbal-bal) - monitor

You mean that the Gain levels should not be above zero in any part of the route and the amp volume set to half at max?

What about the gain and output levels of the guitar processor(no gain no drive)?Is it ok to turn them near max?

Thanks for the help so far...I extremely appreciate it

the routing is fine

Gain levels should be within spec.
learn about Gain Structure in general.
... then you had to go and mention guitars and guitar effects
:roll:
err
yes there are rules but guitars are one area where rules get broken ... often.
Hard edged clipping is probably not what you want so use your ears and if it sounds cool you are probably close.

I was more interested in the console to amp connection.

I'll see if I can finds some specs on the Soundcraft Compact-4 and the Technics SU-Z22 Amplifier
...
and draw up something that makes sense.

I think I' ll try trial and error about the guitar levels, then.
If you find find anything useful about the console-amp connection let me know, I'll be happy 8) Thanks again for your help!