There is no sound in German like the English w, as in where, who, when. The German w is always pronounced like the English v and German qu as English k-v. The German v can take the same sound as the German w (English v) but more often it is pronounced as the German and English f.
V (as f) - das Veilchen, davon, vergeben, viel, vier, das Volk ...
V (as german w english v) mostly for words of foreign origin - David, devot, Ventil, vulgär,
if it's a foreign word, feel free to make a short, subtle U sound after the Q , but no "profound" W sound
after all languages that have no Q in their alphabet even made those words be written e.g. with kv instead (or X = "short version of "ks", so they don't have that either)
if it's a German word, (Quelle = source;also spring/well .. as in fetch water from it)
use a V sound, would/might sound weird if you didn't
..^^except for maybe:
- "Was/wie macht der Frosch? Quak!"
so you can determine whether it's that or curd = Quark (with a V sound)
also it's the way kids would croak, as they might not have moved from the qu sound too much yet... although the action of the croaking (das Quaken) would get the V again by most :)
just like in English you can use Quality like "Attribute" or "The nature of something"
Die Qualität ist die: Beschaffenheit / Eigenschaft / die Natur einer Sache = dessen Natur
so it's not limited to whether something has a high or low quality, but the quality of something has the description or the attributes, the -whether unique or not- factors/facettes within