Luxman SQ-N100 noise

Hi everyone, I have a strange problem with my Luxman integrated valve amp. When I listen to it there is unfortunate crackling and noise superimposed randomly on the music however if I push in the line direct button this noise goes away. Should I replace the preamp stage valves (ECC82 and ECC83) or is there another solution people might recommend. Source is a range of iPods, a technics turntable, a Sony D6C tape player and speakers are Rogers LS2a/2 or headphones Audio Technica W5000.