Ideas for a 2-in-1 frankenbuild

Hi all, I'm new to the forums, been enjoying Linus' youtube videos for a long while and was hoping you guys might be able to provide some input on a bit of a silly idea I have for a build.

Currently I'm using an iMac and an old pc with a secondary monitor as my home setup; I have the audio from the pc piped in through the iMac's audio In and played back using Audio Hijack Pro. This allows me to use one set of headphones on my mac while listening to iTunes or using VoiceChat, and playing a windows game on my Windows Machine. I also have a simple HDMI splitter so while working I have the display set to the mac, and while gaming on the pc I can still use the iMac's own screen to browse the internet.

I'm looking to replace this current setup with single Hackintosh, and I had a bit of a crazy idea. It's probably quite impractical but I'd like to hear your thoughts on it.

First, here's the configuration for the basic build, Intended to basically be powerful enough to play most current games at 1080p, 60fps: When working I would be using it as a mac, and while gaming I'd reboot into windows.

However I want to be able to maintain the convenience of being able to reboot or play a fullscreen game while still having voice chat, iTunes, etc running separately of the main machine, and not having to tab out of the game, or worry about audio levels changing on me.

So I'm wondering, is it possible to fit this build in a case that would leave enough room for a small secondary pc, like at a mini-itx scale, so a 2-in-1 build where the smaller media pc would be dedicated to managing audio, allow for basic web browsing, etc?

I realize it would probably be far more practical to just get a mini-itx case as well, but I just love the idea of including a mini-itx or smaller in place of the usual 5.25" bay location, or in place of where you normally have a 3.5" drive cage.

Has anyone attempted or heard of something like this? What kind of a case do you think might be worth considering for this (admittedly quite silly) idea? I love the look of the Corsair Obsidian 450D, and possibly the Corsair Carbide 540, the latter of which seems like it might have enough space in its back section for a mini-itx mobo.

Anyways, I'd love to hear your thoughts, even if it's just to tell me it's a stupid idea :P

It would obviously require some Alabamer engineering to get it to work, but sure, there's a way to do anything you want... 

By the time you got through, however, you'll likely find an HTPC audio box + mid sized tower computer would take up less space than the full tower monstrosity you hinted at... after all the jury-rigging, extra wiring, holes drilled/cutout from the case for buttons and ports, cable management, etc, it might make a man appreciate the simplicity of onboard power buttons and usb 3.0 ports :P

Doable, yes... Practical? meh...

Here's the same computer, with better components for the most part, for $300 cheaper... enough to pay for the HTPC case and whatever you need to finish it off...