Digital music: best quality music

best quality music

I am new to digital music. I have fairly high end reciever Denon2309 and PSB Synchrony two speakers. My question is, what gives me the highest quality sound reproduction? Is it an IPOD? Are different download sites of better quality than others?Should I burn my digital music to CD's,or that a waste of time?Are the sites where you pay for downloads better quality than the free ones? Or should I just buy the CD's in a store for best quality sound? Are there software upgrades to copy tunes at a higher quality? Wow ,is that enough questions for my first request?