provisus,quinto,gradofan2 thanks for your replies.
Something that i'm afraid of,is that if i buy little pinkie psu and something goes wrong and damage the amp then warranty is voided.
I wanna ask something else:Sometimes when my headphones are already connected to the amp(and i wear them) and then i put the mains plug on the wall,after 4-5 seconds i hear an instant fssst sound(that last only a moment)first from the right driver and then immediately from the left.I suppose that this is normal(something associated with the tubes i guess).But the strange thing is that,although this fsst sound is always the same from the right driver,sometimes the left driver doesn't make this same sound,but a loud "pop".(not too loud).This sound is audible even if i don't wear the headphones.
I called musical fidelity(england) and they told me it's not a problem but it would be better if i connect the headphones after i had connected the amp to the wall.
do you have any similar experience?