Could someone please explain to me why with the HDMI audio override in the on position on my V+ box, ITV HD channel can still be heard thru the tv speakers, yet the other HD channels need to have the amp on as expected.
Yes, that's right. However my amp processes stereo to give excellant Dolby ProLogic which, though not as dynamic as DD, gives excellent surround sound and sub-base via an 'optical digital' cable from my Virgin Media V+ box.