Audio Research VT80SE amp vs Prima Luna EVO 400 or 300

What setting do you prefer with your current MFA's?

Ultralinear (sp?) or triode.

If triode you may be open to lower powered (< 60 watt) tube amps with beefier power supplies.

DeKay

Obviously, the only true way to tell how they sound is to demo them. in your system. If this can't be done, at least compare what each amp has to offer. The Evo series offers balanced inputs and a remote that lets you switch between triode and ultra- linear operation. The Evo can also serve as a mono block should you decide to upgrade to more power. It also offers auto biasing and "bad tube" indicator circuitry. These are all features that may or may not be important to you but at least are worth considering. Both amps are well built with quality components and neither is likely to disappoint, but again, the real test is how they sound in your system.

J.Chip

OP — I went from a Prima Luna HP Dialogue Premium integrated to an ARC 160S amp and REF 6SE preamp.  Never regretted that.  I concede it’s not a fair comparison to start with, but I still use my PL in another room and I’ve obviously made my own mental comparisons (room differences and associated equipment, again, make it an unfair comparison).  Subject to all those caveats: I prefer the ARC house sound.  Clear, liquid, bloomy, transparent, just the right dose of fleshiness.  Not even remotely syrupy or rolled off.  In fact I hesitate to even put those words in the same paragraph as “ARC.” Grip and authority might only be a B+ to a bunch of A+ attributes, but those weren’t high points for the PL, either.  When I went from an earlier tube integrated to the PL, the PL seemed awfully neutral for a tube amp.  A smidge chilly.  Sometimes not the kind of neutral I wanted.  Sometimes fantastic.  But in a battle between my mood and the amp, my mood always won.  So I tried SS for a year (BHK monos with BHK pre — yes, yes, I know they have tubes on the input stage, but that’s not relevant here).  Popped the PL back in and remembered that it does create that dimensionality-plus, levitating sound you only get from tubes.  Intent on a return to tubes, ARC entered my scene and I was smitten.  Fell hard for that sound and added a REF40 / REF75SE / Harbeth 30.2 system in my office.  ARC stuff can win over my ears even when they’re in a bad mood.  That was 18 months ago, so time may change my views.  YMMV.  

How do you find the newer ref 6se / 160s compare to ref 40 / 75se ?

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.