Xiola, when I had an entertainment unit to fit all my gear into it was a major pain to get to the wires. With everything hooked up I had little room to pull out the components to check the wiring. I went searching in my garage and found one of those little dental mirrors (small handle with an angled circular mirror) that I used with a flashlight to make connections. I usually had the manual open turned to the page with the drawn schematic. Not a perfect solution, but it worked.
Finally ended up redecorating and got rid of the entertainment unit and bought an AV rack (open on all sides) and it is soooo much easier to work with.
