Pass INT-30A with Acoustic Zen Adagio

May I suggest Musical Fidelity as another option? Lower price point that McIntosh and similar sound. I think you may find them less analytical than the Pass. I might also suggest Simaudio or Ayre but those are in the same price range as McIntosh.

Can you find a local dealer that would let you try out at home for a while?

I'm currently using a Musical Fidelity integrated amp with a pair of Adagios and think it works very well. I also lean more towards the warm, analog side of things.

I am currently demoing a Rogue Audio Cronus Magnum II integrated.  I am noticing the same thing I did when I used my PrimaLuna Dialogue Premium with the Adagios.  There is a bit of grain somewhere in the treble that these speakers seem to emphasize.  Overall, the Pass is clearly the better amplifier, but the rogue is more forgiving of poor recordings.  But not all is good; for example, the higher octaves of stringed instruments sounds rather strident and aggressive through the Rogue, whereas on the Pass they are presented very well. 

At this point since I am using two different amplifiers and neither of them seem to fit the bill totally for these speakers, I think I should take that as a sign that the speakers need to go.  I think my ears may just have an issue with ribbon tweeters.  I had this same problem with my previous speakers, the Golden Ear Triton Three.  I am probably better off with something that implements a smooth treble using a silk dome tweeter.  It seems harder to find speakers that are voiced more towards a musical sound rather than analytical, since "more detail" is probably what sells.

@jwglista  I am with you on ribbon tweeters silk or even a good metal tweeter sounds much smoother and with plenty of highs for my ears. I will also say the Pass is relatively high end as integrated amps go but both the Primaluna and Rogue are more very good budget gear. Perhaps not just tubes is the answer but better tubes?

Any other thoughts/impressions on the Pass INT amps ?

I have no thoughts on the amp, but I can speak to the speakers. I had them in my system about 6 years ago, and strident or harsh in the high frequencies are the last descriptors I ever thought I would hear in reference to them. I'm glad you are exploring other aspects of your sonic chain to find a solution. 

The ribbon tweeter never induced in me the anguish metal tweeters had in the past, and just like you, I am overly sensitive to those HF nasties. I drove mine with Red Wine Audio 30.2 amp and their Isabellina preamp. Tone, body, warmth, and detailed transparency aplenty.