Hi Defstathiou,
I'm glad to hear you are enjoying your YBA passion integre. I own one too and it's just simple musical bliss. There are a number of tweaks that will bring this integre to a much higher level.
First, I would recommend using both the separate high and low outputs that the YBA offers. This will bring out better transients and improve your micro/macro dynamics to a certain degree. All you need is a second set of speaker cables, in essence almost like true bi-amping ... luckily this is possible with this integre and offers some great advantages.
Secondly, I would highly recommend the symposium series 2+ rollerblocks (doublestacked if possible) instead of the ceramic feet used. Some critics say YBA sounds polite. Not so with the rollerblocks. Audition them if you can, they will never leave your system, this much I guarantee! They make a BIG difference. And if you can, get a granite block under the rollerblocks, it will tighten the lowend even further.
Lastly, consider upgrading the powercord to a Revelation Audio Labs PRECEPT or Shunyata Anaconda, either of these 2 has worked very well with this amp and were worth the investment. With them I have found that I do not need the large YBA Passion 1000 monos unless I had a large room which I don't.
One last thing, the preamp of this integre is its weak link. The amp is first class, but you need an Audio Aero cd player with a inbuilt preamp to find that out.