switching circuits available anywhere?

[screamersusa]

are there any simple switching circuits anywhere that can be grafted into
existing amps as isolated controls from +12 to +15 supplies?
In other words, spst dpdt remote controlled etc using rat shack parts?
Not physical switches but remote controlled.
Thanks

[defaced]

Sounds like you're looking for a circuit to drive a relay.  Perhaps something like this is what you're envisioning (or a simplified version of it)? http://www.geofex.com/article_folders/fxswitchr/fxswitchr.htm