This should work well for you, though Pyle equipment doesn't have the best reputation. You might prefer this Monoprice amplifier. Its power rating is safe with your six 25-watt transformer/volume controls. It also has the advantage of built-in summing of stereo signals so you hear both left and right signals in all speakers.
The Micca speakers are nice, but I'd go with the 8-inch version (for about the same price) because it will give you better bass response.
Yes, 70 volts is normally considered low voltage though I'd check local electrical codes.
Hope this helps!