TO

 Dejame preguntarte el mismo en español.  Cuando debo conjugar un verbo: 

"iré a escucharé musica" obviamente no es correcto

"iré a escuchar (to hear) musica" queda bien "to hear" = escuhar o sea el verbo en infinitivo.

"Quero aprendo el español" no te parece bien gringo ?

"Quiero aprender(to learn) el español"  to learn = aprender

Lantablamente hay mas ! hay verbos auxiliares, verb phrases, y "to" como una preposition. Pero andamos antes de correr. Espero que te serva 

Thank you!!

Your example sentences are both grammatical, because "go" and "want" both accept verbal complements of the form "to+verb".

For each verb you have to learn whether it accepts verbal complements of the form "to+verb" or whether it doesnt' accept them. There is no rule to determine this automatically.

By the way, your sentence "I will go to hear music" is a little strange; most people would say "I will go to listen to music". The verb "to hear" typically is passive, unintentional, or without attention, while "to listen to" is active intentional, or with attention. The same distinction exists for the verbs "see" (passive, unintentiona, without attention) and "watch" (active, intentional, with attention).

"to" prep. = a, para, por,de, hasta, en, que

I came to see you=vine a verte,  I need it for my work=lo necesito para mi trabajo,  from here to  my office (hasta), in to the bottle (en), what is there to do(que)

delante de un verbo indica solo el infinitivo y no se traduce. to speak  hablar, to eat comer,  to sleep dormir

"to" adv. hacia determinado objecto    he came to =volvio en si (tilde sobre volvio y si)