Setting up music on a boat

No.. it won't work because Time Capsule is not a media storage device.. it has no extensions and no ability to play media.

The apple system needs an itunes running somewhere on a computer. eg a mac mini would work. You don't need a new one.. grab 2011 or 2012 model and put in 1TB disk.

Nope.. because itunes on the ipad must connect to itunes server (no such thing but that is how it works) or iCloud.

You can of course buy something that is non apple that has an itunes server in it.. how well an ipad will co-operate with say itunes server in a WD MyCloud I don't know. Many commercial NAS solutions have itunes available.. but how well apple gets on with 3rd party itunes I am not sure.

http://community.wd.com/t5/My-Cloud/play-music-stored-on-mycloud-in-ipad-music-p layer/td-p/631241

Apple is highly restrictive due to the copyright. That is why they don't like people using other systems.

Sonos on the other hand can play songs from an itunes library stored on the TC. Look up sonos and there is likely an ipad app to control the sonos.. again this is outside my network interest area..

https://en.community.sonos.com/music-services-and-sources-228994/import-music-fr om-ipad-29383

An mac mini would be able to stream the music, store the files, and provide the feed (wired, wireless, or bluetooth) to the amp and keep your ipad for nav (or connected to the itunes on the mini for control of the unit via wifi that the mini can transmit without need of a router.) Added benefit is being able to also play video content to the ipad, etc. For a commercial application it could be a welcome aboard message or drive advertising while in-dock. I have used external "nas" drives and storage devices from WD, Seagate, and EMC. They all initially had apps that worked on ios devices, but historically when a new device comes out they put maintenance of the apps on low priority creating an unstable and problematic system. (I've spent days trying to figure out why the app stopped working with the server to find out a security update occurred that hasn't been updated on the app or vise versa.) Also an external nas would require a transmitter to project the content as they do not normally include bluetooth or wifi base station capability.