I had an earlier Zamp with less power, and I was pretty surprised at the power it had. It drove some 92dB two ways easily. But to be honest I don't ever listen at concert levels. No doubt that the 90-95 rated WPC of the units in mono would more than satisfy your needs, in the worst case scenario. But I imagine a single unit in stereo would do, if you're not into rattling the windows. Either way, still relatively good budget/performance factor. Plus they come up on ebay regularly.
The Zamp was also a badass K340 amp, didn't have the K1000 yet.