How can i hook up 6 mids on a ZR 120

You can do four mids without too much trouble.  Each mid is a 4-ohm load, and the amplifier is 2-ohm stable in stereo mode.  So for each channel, use two of the mids wired parallel with each other.  This way, each channel of the amp will see a 2-ohm load.  You'll get 60 Watts per channel out of this setup, which is the most that amp is good for.

Scott Gardner

You can also hook all the speakers up in parallel, like Scott described above, it will have 3 speakers per channel, now this may be beyond what the amp is designed for but seeing as they are mids that don't draw a huge amount of current (unlike 3 subs per channel) you may be OK, keep the gain turned down for sure, no bass boost etc. Try it and find out, if the amp shuts off, it may be due to overheating, which means, disconnect 1 pair of mids, then try again.