Well in case it sounded like a good idea, dyneema through nylon rubbing over metal as an un-redundant top rope anchor is a bad idea. First of all, anchors MUST be redundant.  Every time.  All the time.  An exception from this rule is a roll of the dice. Dyneema and nylon aren't buddies.  Carabiners at each side of any flacid, wily loop will generally keep a system in line, but with their evil forces combined, dyneema and nylon, dyneema and dyneema, nyon and nylon are a bad bunch.  Nylon won't melt a carabiner.  Neither will dyneema.  Nylon will melt nylon, though, dyneema will melt nylon, and dyneema on dyneema will impinge and then cut itself.   All could have been solved however by making a redundant anchor with "metal to nylon, and nylon to metal".