Audiolab Amplificateur 8300A Argent

Sounds powerful with clear and accurate presentation but emits a hum which can be heard throughout the room. Made worse since the unit is placed on a hard surface. Shame I really like the build and sound quality and having returned it wondering if it was specific to the unit I bought or a general feature of the make. Perhaps the phono needed grounding? I don't have a record deck. Been into hi-fi separates since the 1960's and was glad when tape and cassette decks came along and to a large extent replaced vinyl - too many crackles and surface noise for me.