Interesting conundrum

I had an audiophile buddy over last weekend and we spent Saturday afternoon listening to music using my Cary211 AE amps. After dinner, I swapped out the Cary amps for Odyssey Audio Kismet References. The Cary Audio have a very relaxed and involving but detailed presentation. The Kismets are excellent but we always prefer the tube amps. 
I was just playing music off my server and nothing caught our attention until I played a HiRez file ; Hey Nineteen by Steely Dan. As it was playing I was thinking to myself that this recording was over the top. When it ended my buddy said play another song off the album so I did Babylon Sister. At the end of the song I hit pause and we talked about what we had just heard. The Kismets were giving the Cary amps a real run for the money. I tried a regular cd download and it wasn’t anywhere near as involving. Mp  3 was next and we both agreed that the Kismets were showing stark differences between the different formats. On the other hand unless a recording is just plain awful the Cary’s seem to have a good , better or best sound presentation with just about all recordings.
The Kismets have Cardas rca Clear Beyond and Synergistic Research precision reference power cables and the Cary’s have Synergistic Research Atmosphere Level 4 XLR and Voodoo Air Dragon power cords. Both amps are using Cardas Clear Beyond speaker cables feeding my Tekton Design Ulfberhts. All the amps have the same equipment connected to them.Any ideas why Kismets are so unforgiving whereas the Cary’s are very democratic?
You are not doing anything close to an apples to apples comparison. Your cords are inconsistent between the two setups, so you have no firm conclusion. The only thing you can say is, "I like this setup better," but you are far from being able to say you prefer the one amp to the other. 

The ideal in all such comparisons would be to have a consistent loom/suite of cables from one manufacturer across the board, and if comparing to another brand, have an entire set of them as well. Most audiophiles do not wish to spend the money and/or take the time to do such comparisons. 

Just the fact that you are using different brand RCA and XLR cables changes the entire system enough that it invalidates the comparison if you think you are hearing the amps. 

For starters, try swapping the power cords between amps, leaving all else untouched. 

If you cannot get consistency between the interconnects, grab another brand/model of speaker cable and swap that also between the amps. My guess is you will have a fundamental reevaluation that may confirm, or very possibly overthrow your previous conclusion.  :) 

Bottom line: Nothing wrong with getting impressions of different systems, but you have not isolated the amps enough to render judgment on them to make any firm decision as to which one to crown the winner. 
Right. I'm always puzzled by people who change three things and then act like its just one.

Makes me wonder, if they aren't aware such obvious things matter, what else are they missing?
Douglas thanks for the detailed response. I have swapped the cables around and this current configuration brings out the best in the amps. For some reason the Kismets work better with rca connectors and Cary’s  xlr’s. I have had the Cary’s for years and the Kismets for only a couple. The Voodoo Air Dragon was designed with tube amps in mind but I did try it on the Kismets. The Synergistic Research cable sounded better than the Voodoo on the Kismets. 
@millercarbon the current cable configuration has been in place for at least 6 months after I spent a lot of time moving the cables around and listening to what they were or were not doing.
Cary amps seem to be voiced that way. Very euphoric and warm - anecdotally warm. The Kismets are telling you like it is. I wonder if the output tubes are getting tired in the Cary.
@ noromance good point on the output tubes. I have been thinking about replacing them but the ones I am looking at aren’t cheap but they are on my list to do during the next few months. I have another Audiophile friend coming over for the weekend before he and his wife get here I will check the bias.

You see this effect with other equipment. When I compare both Hi Res and Vinyl versions of the same recording the vinyl always sounds nice and the digital depends on the recording. So, noromance is right. The coloration (harmonic distortion) of the Cary's and in my case the vinyl lend a euphoric element that over rides the actual sound quality of the recording. Digital is more accurate but in many instances analog just sounds better. Sounding better and accurate are not the same thing and are at times wildly at odds with each other. Like Nelson Pass says," Audiophiles just want to be happy." So he adds some harmonic distortion to his stuff.
Big differences, even between similar types (i.e. SS vs SS, or tube vs. tube) are to be expected. This is normal. 

Ignorance, that is, lack of experience in comparing, can cause a person to be content, but it also is the enemy of progress and better sound. When you do comparisons you find out there IS far better sound to be had. So, be prepared to open your wallet to get it. If you don't want to spend money, stop comparing. Simple. But, I suspect you had some reservations, problems with your amp's sound, or else you may not have been comparing. 

So, you're working the permutations, good! So, there's no problem here, just different outcomes based on what each amp does. No big deal. If you are not perfectly content with either one, now that you have heard the variance, keep looking. You'll find your "perfect" if you keep at it. 

My goal in system building has been to accept no significant shortcomings and to be eminently content with the sound of all media/music played back. That is far harder to do than it might seem. Even systems at $40-50K can have troubles in certain aspects of performance. So, don't be upset if an affordable system has some shortcomings. 

Beside the above mentioned variables: there are a plethora of EL34/6CA7, 6SL7 or 6SN7, 300B, 845 or 211 tubes out there, that will also make major differences, in presentation.      Running A or A-2?      Bias settings?      Feedback level?      Then; there are the Cary’s oil-filled caps.      The possibilities(to vary your sound), are myriad.
Leave the Kismets on for a week+, or longer if you can, do not shut them off, or power them down before a clinical ear test.
then compare.  The odyssey stuff is very nice sounding.  It’s the cousin to Symphonic line amps, which are world class top tier respected power maps.