It's kinda hard to say seeing as my life is always changing and what not so saying a specific band? No can do. However music has really defined me the past few years. Here's a little story.
In late 2005 I still had horrible taste in music, but I discovered Steve Vai, a guitarist with a finger in every music style around and it really opened my mind to what one guy can do with so many different sounds/style, so naturally through him I discovered Frank Zappa and I am still discovering Frank Zappa three years and 40 CDs later. The guy is the best thing in music. Ever. His comedy, his politics, his very approach to music speaks in levels very few are even near. Being a disenfranchised youth formerly of the suicidal/emo metalhead persuassion this blew my mind and such, he got me interested into music as an art, as an ideal, and how barriers can so easily be broken by music. His slick fluid guitaring is a major influence on my own. He got me into composing seriously, and while the stuff I do is kinda opposite to his music but I'd say what I've learnt and still learn from him is the major input into it.
Through Zappa I got into Freakout music and fusion and jazz and whatnot (and again still,always delving into these) where the openness in the music is just awe inspiring. Thigns lead to another, fusion and freakout lead to prog, prog lead to Canterbury Scene. Be about the time I'd left GW last year due to whatever troubles, and was really down. Kevin Ayers laid back approach to life became an ideal, but more importantly the acid fueld phillosophy of Gong frontman Daevid Allen really knocked some sense into me about how I see the world, and how I can see the world if I wanted. His lucid dream like sense of reality and purely open optimistic view of the world are things I am heading towards, and have helped me in a great many ways come to terms with so much.
Thanks to Daevid Allen I got really into space-rock lately as well. I've made one ambiant/new-age album and working on another (both instrumental experiences based on visions I've had around these new ideals I'm discovering), whilst also working on an Acid Mothers Temple influenced project. Discovering people like Zappa, Ayers and Allen allowed me to realise that I can be myself, and not need to compromise to other people's expectations, I can persue my own interests and passions and not pay attention to naysayers. It's changed my whole world outlook, my music outlook and as a painter I am finding myself being more influenced by what music I am listening to than the objective of the painting.
To be honest while I tend to stay quite far away from GW's music club, the whole DIY music attitude this place has is absolutely astounding and strongly inspirational, as an extremely amature musician myself, to see people like ATARI and DJ Soup releasing so many projects, seemingly uncompromising, it's really cool.