I've been a fan of the SRS iWow audio adapter for my iPod Classic for a number of years. What this dongle did is make iTunes audio sound dramatically better. It tightened the bass, improved the treble and added a good deal of presence to my music with the largest difference being heard in acoustic or orchestral tracks. It also punched up the audio of videos to an extent.
This wasn't done by just increasing the volume, which would be the easy way. Instead, it added proprietary post processing to improve the sound. The downsides were that there were no settings outside of on or off, it was rather big and clunky, and it reduced iPod battery life by 26 percent.
At Macworld 2011, I met with Shawn Kamal, an engineer
