Cheap Music Mixing Software?

I wasn't surely exactly which forum to ask but here goes.

I have noticed that different downloads of specific music songs or productions treat different frequencies differently. Case in point: I down loaded some of Yani's stuff and decided I like it so much that I purchased one of his CDs. However, I noticed that one specific prodution was much richer in its base frequencies. The Downloaded piece had heavier emphasis on the lower frequencies, so much so, that I was disappointed in the purchased CD. The added base made the music fuller and richer.

My Question: Is it possible to purchase software thru which I can convert purchased CDs to MP3 format, manipulate frequency loudness on my PC, then reburn to blank CDs? Cost consideration is important since this will be done purely for my own enjoyment.

Thanks,

JM