I am using Steve McCormack's DNA-500 to drive my Legacy Whispers (lots of drivers, 4 ohms) and couldn't be happier. Only amp I've heard that comes close sonically is the BAT VL-600SE. Mac 501's didn't touch it, nor did Parasound, Rowland or Krell. I was a little hesitant after all the rave reviews for the amp, but got one to try and am not letting go. Haven't heard anything that touches it under 15K except the BAT at 11,300. DNA-500 is 7K list, 500w/900w and loads of current. Remarkable sound - you will be surprised if you hear it!