OK, if we take your example of the baker as "working class" rather than "merchant class", as in, the dude baking the bread, not a wealthy merchant who owns a successful baking operation, then yes, you'd be right. It's highly unlikely that he would have the means to go to an opera or concert.

However, he would still encounter music regularly, most notably in church. Take J.S. Bach, for example (Baroque period, but still the best example). He was employed by his church in Leipzig to not only perform, but write music for the church. What he wrote for the church were primarily cantatas. A cantata is essentially like a sacred, mini orchestral suite with choir and soloists. They're shorter than a symphony (20 minutes is average), but are some of the most beautiful works that Bach wrote.

And rather than writing a handful of these, he wrote HUNDREDS, and each were themed for the particular church date on which they were meant to be performed (2nd Sunday of Advent, 1st Sunday of Lent, Good Friday, Christmas Day etc.). He wrote so many, that you could perform a different one each week, and not run out for 7 years. Many have been lost now, I think there's only 5 years worth that have survived, but the volume of those that survive is still staggering.

Now, not all churches would have had the money that St Thomas in Leipzig had, but music would have formed a large portion of many church ceremonies in varying degrees. Some with full orchestras, some with simple hymns, but still, assuming your baker attended church regularly, he would have heard music there all the time.

Other sources of music for commoners would come more from folk traditions. While we hear about the major composers in Europe during this period, but folk music would have been around well before, during, and after. What kind of music would depend greatly on the country and region in which the baker lived, as folk music is a very regional thing. Your baker may have been taught how to play a pipe, or flute, or other instrument by his father, and play it at home with his children, or his friends might have an instrument and they'll sing folk songs when they get together.