Audio Research VT80SE amp vs Prima Luna EVO 400 or 300

Hey BIF,Yes indeed, I do find ALL the comments here quite helpful, and I intend to investigate the Ref 150 SE and Ref 75SE further.  

One thing @dekay , the only switches on my MFA amps are standby and operate. They take a quad of 6550 or KT-88 each.

@ps 

Some of my earlier ARC amps used 2 quads of 6550 SED Winged C tubes.  The newer ARC amps use KT-150s.  There is no comparison.  The KT-150s have reserve power capabilities that are significantly greater than 6550s and KT-88s. 

When my Ref 150 was upgraded to the SE version, ARC switched out the stock KT-120s for KT-150s.  Major difference, especially in bass.  The mids and high ends were really nice too.  

Google the tube specs on line.

That said, I think the current line Prima Luna line also use KT-150s.  It is worth checking.    

@BIF,
Thanks, and yes, I have learned that the latest Prima Lunas I’m looking into can use KT-150’s. That’s another reason I am interested in them. That, in addition to ease of biasing, gentle driving of tubes, etc, and down-sizing my system somewhat. My mono amps still sound very good but I’m hoping I can improve SQ and do it with a single, newer amp while keeping my Lumi preamp, which of course can only run unbalanced.

@BIF,

Ken Kessler thinks the REF 75SE is the best amp they ever made, current lineup included.  And he literally compiled/authored the latest book about ARC.  So, no, I would not agree with the marketer's notion that the 160S blows away the 150SE or the 75SE.  My ears, and my reading, tell me that ARC has moved 1-2 degrees away from their traditional sound to add a bit of what my teenage ears liked.  But just a smidge.  Then you have flat-out improvements with capacitors, resistors, wiring, etc.  I wouldn't have moved to the 160S in my trophy system if I didn't like it more.  I'll just say this: if they come out with a 260S, I would trade up and sacrifice the 160S for the new toy.  But I will never sell my REF 75SE (or REF40).
And good call on the KT150s for OP.  My 75 always had them, as has the 160S.  But I played around with the EL34s v the KT150s in my PL.  In that amp, I preferred the EL34s (they softened some leading edges, which you can understand me liking from my first note).  But talk about oranges to apples ... the ARC amps that can accommodate KT150s all benefit from that swap, I believe it's fair to say without controversy. 

Lastly, seeing the note about biasing, it's easy on the 75SE.  Child's play.  And gives you one more thing to monitor and kid yourself into thinking you're a participant ...

To quote: "Lastly, seeing the note about biasing, it’s easy on the 75SE. Child’s play. And gives you one more thing to monitor and kid yourself into thinking you’re a participant ..."

My MFA monos are super-easy to bias. The meter is in front as are the controls. I am very comfortable in tube world. :). But maybe I’m just getting soft in my golden years and am starting to look into "set it and forget it." :)

If I go with PL, as good as the E34’s might be, I’ll likely try KT150. I’ll still feel as if I’m a real participant. :)

You fellow tubeaholics rock.

One other thing, is it absolutely the case that the 75SE must use balanced interconnects?  If I keep my Lumi pre I cannot do that.