Alternative Preamplifier 

We examined transistor preamp circuits.  Junction FET's didn't give enough gain.  We tried a BJT circuit - looks good!

	This circuit gives a gain of 8000 between 15kHz and 100kHz
With a component count of 10 its not a complicated circuit to build, and none of the values are too critical.  Even different transistors can be substituted - e.g. BC108
If a 4024 is used as the counter/divider it already has a schmitt input - but I dont know what the parameters are. I'd assume that a simple emitter follower connected to the output could be used to drive headphones directly.