How can I output music from an iPhone to a Bluetooth speaker and at the same time output to another sound appliance where the iPhone is jacked into? Like a Bose stereo device.
I don't know about how a Bluetooth device would work in this context, but you can achieve what you want using WiFi and cabled connections.
1) Use an Apple Airport Express with WiFi. Streaming music and audio to a stereo system is what it is designed for.
Go to an Apple Store or other authorized Apple dealer and explain what you want to do and they can show you how it works.
2) Alternately, wire the headphone output from the iPhone into a semi-professional mixer board which was then connected to more than one amplifier and speaker device. This is equipment used by musicians for recording, and it would require some expertise to learn to use.
Here is a link to a list of small, inexpensive mixers on sale at Guitar Center.
Go to a local music store and tell them what you want to do and they can explain how to do it.
Currently there's no way to do this with a stock iPhone. You could try Jailbreaking the phone and getting some 3rd party software that might allow it, but I'd recommend against that. Honestly I can't imagine Apple would ever build this functionality into iOS. There are ways to accomplish this in code, but I don't think Apple would approve an app that attempted to do this.
There is a 3rd party app by Rogue Amoeba called AirFoil that lets you send audio from an iOS device to multiple outputs. It doesn't do it in the way you described, but it does get the job done.
Use an out board sender/receiver unit. Plugs via 3.5mm ear phone jack. Unit on phone on send mode lasts from 7-10 hrs on a charge via micro USB, sending its Bluetooth signal to another of the same unit. Other unit is switched to receive and changes signal back to RCA red and white for amp... Works well up around 7 meters
Use the Thonet and Vander Multi-Room Bluetooth Audio Hub Router | Connect 22 Bluetooth Devices Simultaneously | 1000 Ft Range | Powered by Cassia
Cassia makes a Bluetooth hub. You can find it at Staples or Amazon.
If you are trying to share to iOS devices check out: