Hi and welcome to the forum. I honestly do not understand your selction of equipment,particularly the one about amplifiers.I mean,no one sounds alike.You;ve got there lush sounding amps and over analytical ones.Anyway,they're all good but there is one particular combination there that i'd go listen to.The ATC scm11 with the Naim Nait 5i.

Hi Firat

Could you please tell me why you chose those particular amps and speakers? Not that they're bad,on the contrary ! is it because you have a dealer that only stock these brands or is it another reason? You do understand i cannot give you any further recommendations.The combinations are many.As for power,unless you opt for difficult load loudspeakers or if you have a hugh room(which you don't) you shouldn't be concerned with such options.My room is larger than yours (18.5 x 23.5) and my loudspeakers although efficient on paper,when Stereophile did a review for them,they found them to be 84.5 db at 8 ohm.My pre amp has a knob that can alter the output between +20 and -20 db. My power amp is rated at 250 wpc at 8 ohn. I can listen to lps (cannot commend on cds since my cd player has an output of 6 volt)at full volume when i have the pre configured at -20 db and i'm just about happy with the spl i can get.No,of course not,i do not listen with the pre configured at -20 db but i wanted to make you understand how much watt we actually use in normal rooms. Well,do the maths.For every 3 db subtracted,halve the power.Instead of -20,for easy of calculations,let's make it -21.Halve the power (250 wpc) seven times (7db x 3 = 21).Yep,2 wpc. yes,i know there are many other variables involved but as i said earlier,unless you have a hugh room and/or difficult load or inefficient loudspeakers,wattage shouldn't be of any concern to you.