All this discussion of the generally very impressive Resolution+ system becomes academic once you turn to HD, since the feature is disabled when an HD source is detected. And actually I'm glad it is, for even without it the 42ZV555D delivers some very likeable HD pictures indeed.
For starters, HD pictures exhibit good (though not world-beating) levels of sharpness and detailing, without being joined by that rather gritty appearance that some sharp HD screens suffer with.
The detailing extends to the amount of subtle picture information you can make out in the shadows during dark scenes too, and also holds up pretty well when there's a lot of motion within a frame. For this, the picture quality probably owes at least some debt of gratitude to the well-judged efforts of the 42ZV555D's 100Hz processing, which is potent enough to make motion look sharper and more fluid, but not so overbearing that it causes artefacts or makes pictures look unnatural.
Yet more good HD news finds colours looking intense, subtle, expansive, expressive and for the most part extremely natural. There are, it has to be said, occasional colour slips with standard def - but no more than we see with many of its rivals, and actually rather less than we've seen with previous Toshiba TVs.
I also personally found the colour balance a touch too warm when watching Blu-rays using the Movie picture preset, but it only took a little tweaking in the colour management system to get things - especially the white balance - more to my tastes.
While the 42ZV555D and its Resolution+ system get most things right, though, the set does come a bit of a cropper when it comes to its black level response.
For however sharp and rich pictures look, there's no disguising the fact that dark scenes on the 42ZV555D look a bit grey around the gills, leaving dark shots like those in the jungle hut near the start of Casino Royale looking a bit hollow and flat in places. Danny noticed a similar issue with the 46ZV555, but it seems worse on the 42in model, lending credence to the fears we raised about the smaller TV's considerably reduced claimed contrast ratio.
It doesn't help the black level situation, either, that the TV has a very limited viewing angle, meaning that black colours turn pretty grey pretty fast once you start watching from anywhere down the TV's sides.
Sonically the 42ZV555D is good - so long as you make sure it's running loud! For while the soundstage seems a bit muffled and indistinct at low volumes, especially if you've got the bass booster turned on (something I'd certainly recommend for movie/drama viewing), unusually for a flat TV, the speakers really spring into life when the volume's cranked up. The soundstage seems wider, more defined, and just generally more credible, though it's still a touch muddy on occasion, and sporadically a particularly deep male voice can cause the bezel to phut slightly.
The 42ZV555D underlines Danny's finding that Resolution+ is a hugely worthwhile technology that genuinely boosts Toshiba's standard definition LCD picture quality to a level up there with the very best of the rest. It's just a pity that on this 42in ZV555 incarnation, at least, the Resolution+ advances haven't been accompanied by similarly large strides forward when it comes to black levels.