There is a lot you are asking for and most of these things are based upon computer settings and not much else. It also uses equipment which isn't typical or common for the average home user to do. And, of course, you are trying to do it on something of a budget.
We have no idea what kind of TVs or speakers you will really be using. It actually helps to list the model number. Kind of like saying "I will be racing a Chevrolet against a Volkwagen... Will I win?" You need to provide far more in the way of specifics to get a real answer.
That said, assuming the DSP from Martin does a good job with internal crossover settings and the like, I wouldn't expect any issues in audio delivery to the speakers.
Video will be output from the graphics card, most typically as 'monitor 2' from the PC. This means that whatever shows up on Monitor 2 will show up everywhere, including if you drag your mouse onto monitor 2. If you have software which supports multiple monitors, including a management piece of software and a playback piece of software, than that software may allow you to control things without interuption.
Your monitor 2 should match the same resolution of the TVs. Do not get a 1080p monitor if your displays are 4K and you are setting the system up for 4K content delivery.
Be aware that you are making a separate physical connection for these two monitors. Monitor 1 is connected to the graphics card on one of the DisplayPort connections.
Your second monitor and ALL THE DISPLAYS will be connected to the HDMI output of the graphics card, and should be sent through a splitter that supports 5+ video outputs.
Assuming this is the product you are talking about...
8-Way 4K HDMI Splitter
www.blustream.co.uk
By the looks of things, this all seems like a reasonable setup.
Make DARN SURE - you are using 18Gb/s HDMI cables from your splitter to the displays if your end-goal is 4K video.
The computer will automatically scale the source material to 4K for playback if that's what you have the PC set to push out. If you set the computer to push out 1080p video, then that's what you will get. The EDID minder in the Bluestream HDMI splitter will help you set that resolution, but you can right click on your Windows Desktop and set that resolution as you choose.
All this said: I would recommend that you consider getting a digital signage player. Products like Brightsign (from Roku), are designed to act as stand-alone player devices that have schedules, playlists, and more which can be setup, configured, changed, etc., while they are playing back video, information, music, etc. without interuption. There are a ton of different players on the market, and they all have a bit of a learning curve. But, once you are comfortable with it, you can update a playlist on the fly while the player just keeps doing its thing. This gets you away from a Windows PC which will go down as software updates occur, and windowing and lockups can occur as well as other problems. Dedicated signage players are for exactly the type of situation you are currently in.
If you need audio out of a signage player which doesn't have audio out, then you can get a HDMI audio extractor.
Brightsign players have several 4K models which have included analog audio output and are just a few hundred bucks.
I will remind you that there is a learning curve with these models and they aren't always drag-and-drop easy to setup.
Explore the various digital signage players offered by BrightSign®, including the revolutionary Series 5, and Series 4.
www.brightsign.biz
