I have noticed a lot of suggestions lately to use solid state relays for
the current switching in automatic musical instruments.  Awhile ago I
purchased 50 75-amp 480-volt Crydom relays.  They use 3 to 32 volts dc
input and switch ac only (they use a zero-crossing switch and will never
turn off with dc).  They are Crydom #d4875 and list for about $65.  If
anyone is interested in real overkill these will do it.  Your branch
fuse or breaker will blow before these things even get warm!  They
measure 1.75 x 2.25 x 1 inches and have screw terminals.  I would be
willing to sell about 20 of them, for $15.00 each including shipping in
the US.