OT: AC/DC adaptors

[Josef Lowder]

Does an AC/DC adaptor need to be an exact match to be safe and not
damage electrical equipment?

I have several dozen "left-over" AC/DC adaptors, but none exactly
match a small Radio Shack mixer that is going through 9-volt batteries
too fast.  And, rather than buying yet another such adaptor, I went
through my collection of left-overs to see if I could find one to
match.  Close, but not quite.

I need a 9v 100 mA adaptor; and in my collection I have one 9v 80 mA
and one 9v 210 mA.  Could either of those be used safely?

One says it can be either a 6v 200 mA or a 7.5v 100 mA which leads me
to think that perhaps there might be some flexibility in this.  I have
a bunch of 9v at various mA ratings, along with a bunch of 3v, 5v, 6v,
8v, 11v, 12v, 15v, 19v at various mA ratings.