Connecting your gear assuming the amp has the proper amount of gain. Your digital source, say computer, cd player, into your DAC. Output of DAC feeding the main line input of your Bose equalizer, output to feed your amp. You will need a cable which has RCA plugs on one end and TRS phone plugs or XLR to connect to your amp.
The tape input of your Bose may work for your bluetooth device if it does not have a digital output. If it does connect to a input on your DAC. If not connect to the tape input of the Bose. Switching the tape input may then serve as your switch for listening to the DAC or the Nokia.
Your volume or gain control would be on your amp. How well it would work for yourself you of course would judge best. For multiple devices is one reason for the addition of a suitable preamp.
Post how you make out. And you may indeed wish to contact Bose if you have not already for their take on the matter. Good luck.
