I have a Wadia 850 that just came back from Great Northern Sound where it received the Statement upgrade; the highest upgrade possible for any of the higher end Wadia units. Now I can't comment on the Audio Aero MKII, because I have not personally heard it. I have had the Acuphase DP75, an Arcam FMJ23, and a YBA Blue Alpha CD1 as well as a few others. I can say that the Acuphase DP75 was better than the standard Wadia 850 and possible 860X, it was close. But after the statement upgrade to the Wadia, the Acuphase isn't even in the same ballpark, IMHO in my system. You can purchase a used 850 and add a Great Northern Sound Statement upgrade, which is not cheap by the way, $2700, all together for around the same price as an Acuphase or Aero Audio, give or take a few dollars. I switched cd players several times looking for the "right" one for my system and my tastes, and have no desire to do so anymore. After the upgrade to my Wadia I am completely satisfied. Can't help on the Audio Aero, sorry about that, wish I had heard it, but I haven't, but the Acuphase doesn't hold a candle to a upgraded Wadia, again in my opinion, since I have had both. Try listening to as many players as you can, you can also call Steve at The Great Northern Sound, which does Wadia and other players and equipment upgrades, if you have any questions about the Wadia or its upgrades. He's a very honest person to talk to, not opinionated about anything. Good luck.