I hear a random low booming noise .

Thanks Swampwalker, do you think this could be from a malfunctioning tube in the amp and/or preamp or would this be a symptom of bigger problem with amp and/or preamp?

Herman, this is a very short and dull "boom" that happens randomly meaning no discernable pattern. I can best describe the sound as like that of a subwoofer, but very short in duration (kind of a pop but at very low frequency). It can be heard between tracks or during, but only in silent or low passages. As far as frequency of occurance goes, it is more of a periodic nuisance than a continuous problem.