I think there are separate devices you can buy a stores that boost your sound, but you'd need to set it up to the USB cord. I think the iHome fits your iPad, which does boost the sound a lot.
Dac's and Amplifiers can increase your volume and performance with LINE OUT DOCK (LOD) from your dock connecter slot. But if you want an equalizer there are some in the app store. I use MyTunesProHD, it has many presets for different outputs such as small speakers, medium and large, ear buds, in ear, over hear headphones, in car. It also has a built in EQ and Auto volume setting. With speed setting too. And it's very own Enhance preset. It's based from the SRS Wow brand, that does a well of a job.
Also theres a catch with the in app pro HD sound package too.
