I've recently bought a Panasonic TX-28DT4 which often hums loudly, seemingly depending on the brightness of the scene displayed at the time. It's loud to the point where it becomes difficult to hear the sound late at night when the volume is down. An engineer was sent out who agreed it does hum quite loud, then later followed this up with a call to say Panasonic are aware of the problem, do not currently have a fix, but would be in touch. It's been a couple of weeks now with no contact. How much noise is acceptable? Does anybody have a quiet one, should I be asking for an exchange TV? Any advice would be appreciated. Cheers, Phill.