People interested in Diamond speaks should look into the silk option tweets for a better, more enjoyable listening experience...the aluminums are quite harsh and belong no where near ear level, should be in kicks IMO- horrible off axis. No wonder the new D6 ,replacement to the M6's, come in braxial form.
Hex's/M6's aluminum versions have been the hardest speaks to work with from my experience. The midbass response for such power hogs that they are was nice, sharp- BUT quite lacking in output.
From the few new D6 setups we've put together they've made improvements as far as midbass is concerned. I'd look into the new stuff.
As far as amps go- D5's are solid, problem free.
I have a d5 300.2 BNIB if anyone interested PM me