Audio Research VT80SE amp vs Prima Luna EVO 400 or 300

I agree with @jjss49 about the sound signatures of both amps.

One thing to consider is the VT80 SE comes with KT150 power tubes, the PL with EL34’s. The PL can also use KT150’s with the flick of a switch.
Using KT150 change the PL from romantic to more dynamic with more bass and treble extension.
That is my experience with the PL Dialogue Premium HP (basically same as Evo 400 minus the balanced connections). Don’t get me wrong the PL DP HP is dynamic, holographic and has great bass and treble extension, there is just more of it with KT150.
The PL will allow you to experiment with several power tubes:
EL34 (and it’s equivalents), KT77, KT88, KT120, KT150.

The AR can use KT120 or KT150

Both the AR and the PL feature auto bias for the power tubes.

Maybe the flexibility of having the option to use several different model power tubes is important to you.
Maybe point to point wiring instead circuit boards is more important to you, as the PL features.
PL also runs the power tubes easier for longer life.

Either way, two great choices.
I would consider what the speakers sound signature is and chose the amp that compliments them.

Ex. Accurate with metal dome or diamond tweeters pick the PL.
Warmer, slightly rolled off sounding
go with the AR.

@ps 
If your preamp doesn't have XLR output you could consider a PL Dialogue Premium HP used instead of the Evo 400 with plenty of money left over to try different 12AU7's in the center position of the amp to dial that sound you and the golden eared wife prefer.

@ps 

Don't hesitate to try different 12AU7 tubes and their variants in the two front center positions on the integrated. They will change the sound characteristics more than any other tube swap.
Although I also changed my power tubes to NOS Mullard EL34 XF2's and was rewarded with a sound with more weight and openess.

Enjoy and experiment with your 60 days....