It depends how loud you turn the amp up, but you shouldn't be connecting different speaker types like that - and it also depends on the power rating of your 100V line speaker!.
Your 8 ohm speaker will take the maximum output from the amplifier, then you add on the wattage rating of the 100V line speaker.
So if the amp is 50W, then the 8 ohm speaker takes 50W, and if the 100V speaker is rated at 10W, then the total drawn is only 60W (or so). But if the 100V speaker is 50W, then you're trying to draw 100W from the 50W amplifier.