Sam_sky

Thanks for the freelancing job recommendation but I am a 70 years old government worker (I am retired with a government pension and some stocks and bonds) so I do not need more income. I do whatever I want whenever I want. 

Distortion can blow out a tweeter because distortion has strong high frequency harmonics.
Try feeding an input directly to the power amplifier without connecting the preamp.

The output of a preamp will produce clipping distortion if the input level is too high. The pickup from an electric guitar produces a level much higher than an FM tuner, a CD player or an MP3 player. Most preamps for a guitar pickup use a Jfet because of its very high input impedance with a gain of only about 1.4 times.   

Nobody makes an LA4058. You got the numbers mixed up, the schematic shows a Sanyo LA4508.
Your 13.6V transformer must feed the rectifiers on the Power Part of the schematic. Maybe you fed the transformer wrongly to the amplifier instead of to the rectifiers? Then probably many parts are destroyed. Your 13.6V transformer will produce a peak of 19.2V and the rectifiers reduce it to +17.2V.
With a 17V supply the LA4508 produces about 6W at clipping into 4 ohms per channel. Who told you 100W? It has fairly high distortion at low and high frequencies and it cuts frequencies above only 5kHz.
Your amplifier probably uses one LA4508 for left woofer and left tweeter and the second LA4508 is probably used for right woofer and right tweeter.