A: Not a stupid question at all! Deciphering all the jargon and abbreviations associated with music technology and pro audio can be a challenging task.
“TS” stands for “tip-sleeve,” a type of 1/4″ phone connector with two sections: the tip (usually carries the positive signal) and the sleeve (usually connected to ground or shield). This type of connector is used for most instrument connections (guitar, keyboard, bass, etc.) and for single-channel (monophonic) audio signals. It is also referred to as “unbalanced,” since there is no separate conductor carrying the negative polarity signal.
“TRS” stands for “tip-ring-sleeve,” a type of 1/4″ connector with three sections: the tip (usually positive), a separate “ring” section (usually carries the negative polarity signal), and the sleeve (usually connected to ground). You may also see this referred to as “balanced,” since the positive, negative, and ground signals are carried separately and can be combined for common mode rejection.
However, TRS connectors can also be used to carry two separate unbalanced signals — a great example is a headphone connector. In this case, the tip carries the positive signal for one audio channel (either right or left) and the ring carries the other channel’s positive signal; the sleeve serves as ground for both channels.
TRS connectors are also sometimes used to carry two completely different signals, as is common with “insert” jacks. These connections use the tip to carry the positive unbalanced signal for input or output, while the ring carries the positive signal for the complementary unbalanced input or output signal. Once again, the sleeve carries ground for both signals.