Update

For some reason I am now able to crank the Lepai LVPIN LP-2020A+ amp up to 100% while hooked up to the Jantzen coil.  (Yesterday the max was 60%.)  And it didn't take but a few minutes to get hot (a first).  Sweet! 

The trick seems to be to turn the amp on, crank it up to 100%, and ignore it as it kicks 'off' then back 'on' again (this will happen a few times).  (You can hear it click when it does this.)  It will shortly stay 'on' and remain so without kicking 'off' again.  An indicator that it is 'on' is that the blue illuminated ring outside of the volume knob will rapidly flicker. 

I don't know if this is a good thing or if the amp is acting up.  At $22.95, I'll take my chances.

Also, I Googled whether or not it's okay to leave one channel of the amp without anything hooked up to it and the general consensus is that it shouldn't be a problem. (Whew!)

At 100%, I get 10 minutes of use before it gets hot and is too uncomfortable to hold.  I still don't have a handle for it but the excess heat causes resistance.  So it's best to stop and let it cool down - which fortunately doesn't take long.  (Btw, users have reported that the Klemens Super P Magnetic Pulser gets hot after about 10 minutes.  So this is another good sign for this DIY unit.)

Fascinating stuff!