Rogue Atlas Magnum sounds bright -- any recommendations?

As Ralph Karsten (atmasphere) has been saying, distortion is perceived as tonality. Less high frequency distortion = less brightness.

Less high frequency distortion = less brightness.

Correct more air and transparency. This goes for the tweeters also.

Have you ever heard a plasma tweeter? The least distortion of any HF driver, because the plasma flame is the diaphragm and it has no mass, the highs just dance in front of you in 3d space, like fireflies that you reach out and touch. next in line are ESL’s and then so-on down the line.

Cheers George

Hifiman,
I have the Platinum-upgraded version of the DNA .05, but when I recently heard Don Sachs' KT 88 amp, I was flummoxed... it has vastly more three-dimensional sound, no question, and a potent LF response, that did not expect in comparison to the McCormack amp.  

I ordered some NOS GE 5751 tubes to swap out for the stock 12AX7's to see if that tames the brightness I am perceiving.  I have little room to move here other than swapping input tubes.  It is quite a fine amp, but for the brightness I am hearing.  

Is the unit new? how long has it been running? I am thinking break in... tubes caps.. If used, how long did it sit?

I would definitely say try rolling tubes and can the amp use power tubes besides the KT90s?