Electrical apparatus for use with musical instruments, namely, amplifiers for use with guitars, bass guitars, musical keyboard instruments, and musical instruments; audio processing equipment, namely, audio signal processors for processing musical instrument audio signals; audio processing equipment for musical instrument effects, namely, sound reverberation units, echo sounding devices, and structural parts thereof; electrical circuit boards for musical instrument amplifiers for the purpose of tube amplification, volume and tone control, overdrive and sustained overdrive, non-overdrive, reverberation, and tube reverberation; speaker cabinets for loudspeakers; musical instrument amplifiers; extension speaker enclosures; speaker enclosures; loudspeakers; components and accessories for guitar, bass, keyboard, and musical instrument amplifiers, namely, electronic effect foot pedals for use with sound amplifiers, and electric switches for amplifiers; replacement structural parts for amplifiers for use with guitars, bass guitars, musical keyboard instruments, and musical instruments; and downloadable instructional manuals for all the aforesaid goods, sold as unit therewith