Quite a bit of leading the witness here.
You made a huge, complicated, time-consuming, expensive, stressful, anxiety-producing bet on the attic location -- and you
won! I was very proud of you, and happy for you, on that!
The room catapulted the sound into the league of what we all strive for: recreating the sound of an original musical experience with significant suspension of disbelief. That is what this new room allowed you to achieve. In the apartment the system sounded like we were listening to nice speakers on an expensive stereo system.
It is impossible to quantify what component or tweak represents what percentage of the improvement in your sound quality, or what percentage of the absolute magnitude of your sound quality. The equipment components were held constant, and the balanced power/isolation transformer was held constant, between the apartment and the house.
I have always believed that the room is the most important component, and my belief in that has only grown over time. This is a silly and invalid exercise but if you want me to try to quantify the significance of the new room versus the new tweaks (beyond the balanced power/isolation transformer which you also had in the apartment) I would say the room is responsible for 90% to 95% of the improvement.
Putting it differently, if you had added all of the new tweaks to the system in the apartment the system in the apartment still would have sounded merely like nice speakers in an expensive stereo system.
Marc, what can I tell you? Your hyperbolic (to me) written descriptions make me think that you are mis-quantifying the magnitude of improvement occasioned by the recent tweaks.
I am very flattered, and I appreciate, that my unequivocal thumbs up meant a lot to you. I was very relieved to hear from your system in the new room that I could give you that thumbs up totally honestly!