Accuphase dp75v vs dp67

i'm Francesco from Milano - Italy,
i've a dp55v and i'm think to
upgrade my cdp with the old dp75v or
the new 67, what do you think about?

As a 75V owner, it is my understanding that the DAC technolgy in the DP-85 and DP-75V relative to redbook is identical. As the 85 is still current, it would be untenable for Accuphase to have the 67 sound better than than the 85 which costs considerably more. The advantage the 67 has over the 75V is the SACD capability. However, if this is not a major concern, I think you might be better advised to seek out a used 75V.
I haven't heard the DP-67, but I compared the DP-75V to the DP-77, and the 75V was a much better unit: harmonically richer, smoother and very detailed - just like a good analog rig. For me the DP-75V is an absolute reference for redbook CD's. The DP-77 is good for redbook, but nowhere as refined as the 75V.
The Dp-67 is new in the line-up as a upgrade for the old Dp-65v. The Dp-55v is much more detailed, warmer, less digital to my ear than the old Dp-65v. Even though the Dp-65v has a superior build. The Dp-67 takes the 55v from 48 khz to 96 khz. Since where only talking Redbook the Dp-75v still looks mighty attactive at current used prices. And I wouldn't call a Dp-75v old just yet! Why are you looking to upgrade the 55v? It might be on the bottom of the heap as far as Accuphase is concerned, but a sweet little cdp IMO. Your own ears will have to be the judge prior to making any leap. Good Luck!
The Wadia is a nice player but in my opinion the DP-75V is more harmonically fleshed out, smoother and more detailed (which shows especially at low SPL's). The Accuphase unit has this intoxicating easiness of presentation, something that I never heard with any other CD player.