Synthesis A 50t

Hi all I’m new on here from the UK and am the proud owner of a synthesis

A50t amplifier which I bought last month my first impressions coming from a class D amp was how detailed it is with amazing separation of instruments and a wall of a soundstage, but! For some reason that I hope someone can help me with is a slight audible hiss when there is not a song playing it’s not loud but I know it’s there I’ve emailed synthesis tech support and am waiting for a reply but thought I could get some answers on here 

thanks in advance Billy G