Buy a iNuke 3000dsp, or the newer version of it, for the VBSSs. Use the internal DSP to control the xover points for the VBSS.
Set your xover on the Yamaha to 80hz. The internal xover on the iNuke should allow you to set xover points for the VBSS where you want them.
If I'm wrong, then a MiniDSP 10x10 would be the best way to go. But, that's $600. Not sure where your budget is. A iNuke is a lot cheaper. Either way, the iNuke is a better choice for driving the VBSS than a plate amp. I like options. And, the iNuke gives that to you.
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