Play desktop audio through iPhone speakers using USB connection

Hi. I have transferred my entire iTunes library from home onto my desktop computer in work. However, my desktop in work does not have any speakers. Is there a way to play my iTunes library through the speakers on my iPhone using a USB connection?

I have tried using Home Sharing, but my computer in work is connected to a network and server which (as far as I can tell) makes it impossible for me to connect to the same WiFi network as my iPhone.

My iPhone 4S does not have enough space to hold most of my iTunes library, and it would be nice if I could play it in work when I'm in the office alone.

I should also probably mention that there is a speaker in the office which I can connect my iPhone to using Bluetooth. The desktop computer does not have Bluetooth. My hope is that there is a way to be able to play my entire iTunes library on this Bluetooth speaker, by using my iPhone as a middle-man. If not I guess I'll just have to listen to whatever can fit on my iPhone!

Any help would be greatly appreciated. Thanks!

It sounds like this may be something you're looking for and could use.

"Home Sharing in iOS 4.3 or later, you can stream your entire iTunes library over your home Wi-Fi network from your Mac or PC right to your iPhone, iPad, or iPod touch. …"

https://support.apple.com/en-us/HT202190

How about cutting out the middle man with a Bluetooth dongle for your computer instead?

Something like this: Just an example dongle

dbm - I think that's what I'll do. Thanks for the advice!

pm-r - The problem with that is both devices need to be using the same WiFi, which they aren't in this case. Thanks for your help though. I think I'm going to do what dbm suggested and cut out the middleman with a Bluetooth dongle.