Shocking to see somebody out there with these speakers! I also have the Z92's, I'm sort of biased to tube amps as I really don't have any interest in solid state any more. You could check some integrated amps from Grant Fidelity, ASL,Jolida the JD1000 is a 100wpc amp that ways about 65lbs or so, nice punchy amp. Cary also has a nice 75watt integrated maybe 50lbs? I have the big Jolida 200watt mono amps that work great with mine but they may be a bit of overkill. There is also the ARC REF 110 but I think that may be closer to 80lbs also not exactly a cheap alternative but does work great with these speakers. I've heard the Z92's form as little as 11watt Quads to 200watt monoblocks the speakers are fairly efficient so these amps will sound great and tubes to me really make them sound their best.
Hopes this helps!