When dealing with such very transparent designs, every little change seems monumental.
Case in point, there are some Berning owners who at first, complain that the unit was warm.
OTL's, especially the Berning is about truth, clarity and correct tonality, tubes are what you hear, not an output transformer, therefore tubes can make the biggest difference, CD player, IC's and power cords can also be detrimental to the sound.
Objects that are magnetic, that are nearby can also have negative effects on the sound of the amp.
Even the room becomes more critical, as more HF energy is entering into it.
Speakers can sometimes also be a culprit, many speakers are not truly liner, but in the case of the Merlin's, I assure you, this is not the so.
It takes patience and some getting use to the truth and as one interested Berning customer reminded me of a movie with Jack Nicklison, truth....., you can't handle the truth :)
Truth comes with a price, you need to have nothing in your system causing trouble, the amp will not correct for that, it will not mask it or change it.
The Berning is certainly not an amp for everyone and neither are Merlin's speakers for everyone but those of you who have this combination and have worked out the rest of the system, you an I know that there is nothing else out there to compare