If it were me...
I would setup the speakers to 16 watts of power draw and get a couple of these amplifiers:
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The amplifier listed, for well under $100 shipped for TWO of them to your door, provides 1 channels of power at 200 watts per channel, into a 70v system.
You will need a stereo to mono summing adapter as well as a small DA to split the audio to the two amps. That's actually really easy and potentially you could just 'Y' the cabling. I would still use a audio summing adapter though.
Extron ASA 141 Audio Summing Adapter 60-804-01.
www.ebay.com
This will take your stereo audio RCA source and mix it down to mono for distribution through the space.
I would get a separate Bluetooth receiver if I wanted Bluetooth in the system, or I would just hook up a mixer of some sort so I could play multiple sources through the amplifier. Mixers can be had for not a lot of money and give you the ability to add other sources or even a microphone if you wanted to.
For reference: 100v systems are used in European nations typically. So, any speakers that include 100v power settings are doing so for our friends overseas.
70v systems are used in the USA and are what the power amps will deliver. So, when you set the potentiometer (pot) to any specific number on the speaker, you want to look at the 70v power draw that it will need, not the 100v power draw.
As mentioned previously, it is very much illegal to play over the air music in a commercial space. If caught, it will potentially be thousands of dollars in fines for the owner of the establishment. There is commercial Pandora and other options out there which can be played back. You also better believe that the first time someone catches the space playing this music will not be the last time the space is checked. Twenty years of speeding and not getting a ticket is lucky, but you still are open to getting that ticket. Same thing here with music playback.