Could some one explain how the difference between the Spektor, Zensor, Oberon and Opticon series in terms of sound? It would be great to know the basis of the hierarchy of which ones supersedes the other. Also with in the series (say for example Oberon 5 and 7) and also how say a how an Opticon 5 maybe a better purchase than the Oberon 7? I don't know if I am wording these things right, but I would love to get an opinion to make my choice easier.