Yesterday I noticed for the first time a crackling sound coming from my right 'speaker in between changing disks. The sound disappeared after about 10 seconds, but then after some investigation I found that both speakers have the same crackling if I leave the source off but turn my pre-amp volume dial up to maximum. I never usually turn the volume pot past 10 o'clock on the pre-amp, so naturally this was a bit of a surprise to me. The right 'speaker crackle is louder than the left, but both are noticeable with the volume turned all the way up. I can't hear anything with the volume in a "normal" position, i.e. under 1 o'clock. The crackle is only noticeable from the "cd" input, and only when the CD player is switched on. Given that I have never noticed this before, is it likely that this noise is being created by the tube output stage in the CD player - the sound only appears about 30 seconds after the CDP is switched on - i.e. after the valve has gone though its warm-up stage. Plugging the CDP into a different pre-amp input still maintains the same sound when the volume is turned up beyond 1 o'clock when the pre-amp is switched to that input. Can anyone tell me if this is anything to worry about? Does the valve need replacing or re-seating or is this completely normal for valve-equipped kit? Thanks all Neil