Hey, if you're looking at Parasound, the 275 amp is a big step up from the Z amp, at 90 wpc and having better specs across the board. If you're ok with B stock, you can get one here for 200 off.
http://https//www.safeandsoundhq.com/products/parasound-model-275-v-2-two-channel-power-amplifier-b-stock-full-warranty
http://https//www.safeandsoundhq.com/products/parasound-model-275-v-2-two-channel-power-amplifier-b-stock-full-warranty