Before we begin, thanks a lot to everyone and especially FransN and Diki for your help in the previous thread.
Now for the headphones.
I plugged them in for the first time about 1 hour ago. In a few words: Oh, my God, what a difference. Simple as that.
The amplifier was already running, I simply unplugged the old pair, plugged in the Sonys, turned the volume to 3/10 and then I thought it was raining.
I am not exaggerating, I just realised how much hiss my amplifier produces, even in low-moderate volume. Unplugged the Sonys, plugged in the old ones, and then silence, with a slight hiss in the distant background. Turned the volume to 6/10, the hiss incerased as expected, and then plugged in the Sonys, and was instantly transferred to Niagara Falls. I really can't stand having the headphones on my ears any more, when simply browsing, or writing a post like this, the hiss is that noticeable.
Loaded Hypersonic, played a little and realised that the adjustments I made to a drum kit using the old pair of headphones, to get it to suit my taste, were making it sound plastic and Mp3ish. I reset the kit and normal sound returned.
Deep bass I never thought existed and also, I loaded a flac file of "The music of the night" from the Phantom of the Opera, which I have heard at least 200 times, and in a quiet passage I heard for the first time in my life the faint "click" sound the singer's lips make when he opens his mouth to inhale, just before he sings a line.
I am a happy camper!!!
PS I also managed to squeeze another 10 Euros in discount. Final price 90€, worth every penny.