Usually (I think), when there is a determiner 'THE' before a noun, we're talking about a specific thing referring to the noun (in this case a guitar)  . But this is a phraseological analysis and I don't think it's the case of this sentence...maybe there's no difference at all..anyway, it depends on the context.

P.S. Sorry for my English not really perfect ;)

Usually (I think), when there is a determiner the before a noun, we're talking about a specific thing referring to the noun (in this case a guitar). But this is a phraseological analysis and I don't think it's the case for this sentence … maybe there's no difference at all … anyway, it depends on the context.

P.S. Sorry for my English not really perfect ;)