I was looking for a reasonably priced ear bud that would fit securely. It also needed to fit relatively flush to my ear, so if I try to sleep on an airplane, the ear bud isn't pressing into my ear. Lastly, and most importantly, it needed to have great sound. The M6 met every criteria. Excellent sound with great bass. Mid range and high end are still clear and crisp. 

Question: What are your impressions about the sound?
Answer: Excellent sound with great bass