We contacted Philips UK (opens in new tab), and the company has come back to us with the following statement on the issue:
"The audible buzz reported on the Forum does appear to be a known problem, although not one we've experienced locally [in the UK] given that the majority of our stock arrives in October.
"The potential issue relates to early supplies of the 40in and 46in PFL9705 LCD/LED sets. The 9705 TVs [like all televisions] contain oscillating electrical components. These components vibrate and emit a humming sound that is inaudible during normal usage.
"All these TVs operate within acceptable noise bandwidths (around 23dB), but we have identified that due to marginal variations in the placement of these vibrating electrical components, a small number of TV sets may emit more noise than others.
"If any consumer is dissatisfied these noise levels, we will of course take swift action to remedy it. Consumers can contact Philips Consumer Care on 0800 331 6015, who will arrange for their TVs to receive a hardware upgrade which will eliminate the issue completely."
We've yet to receive our review sample of the Philips 40PFL9705 due to an unrelated delay with the 3D pack, but we hope to get a full production sample shortly.