Loudspeakers, amplifiers, and headphones links

HT Audio
Theophany Loud Speakers
Arvus - High End Speakers
Audio power - Wikipedia
Loudspeaker - Wikipedia
Efficiency and sensitivity conversion - loudspeaker percent and dB
Diffraction Loss
Zero Feedback Transformer Audio Power Amplifier
Linkwitz Lab - Loudspeaker Design
Speaker Terms
Duncan's Amp Pages
Design_of_the_sound_system
Passive Crossover Design Equations Formulas Calculator
HiFi Loudspeaker Design
KBápps.com
DIY Audio & Video
McMantom.com - Utility
AJ Design calculators
Enclosure Calculators
PLINIUS AUDIO - new zealand
Thiele-Small parameters
Phil Jones Pure Sound
Volume Calc
Eminence
RCF - Precision Transducers
ERSE - Crossover Calculators
SOFTICA SPEAKER CALCULATION PROGRAM 2.0
Norman Koren Vacuum tube audio page
Amplifiers topologies
HeadWize Library
Build a Headphone Graph
Headfonia.com
How Loudspeakers work
hasaudio
Collo's DIY