Interesting you mention room treatment.
There is a whole thread dedicated to it.
If you browse it you’ll notice room treatment isn’t everyone’s taste.
The room is, by far, the weakest part of a music reproduction system. But I believe very few members are aware of that and measured their rooms. Sometimes it is better not to know…
I had a similar approach to yours. Going from SN2 to 252DR/300DR was a disappointment. Treating the room revealed the true potential of the 252DR/300DR.
In terms of sound quality jump, the most significant gains were (for me), by order of magnitude:
- Room treatment
- Speakers
- Electronics (from source to amplification)
But not everyone has a dedicated listening room or can treat/transform a living/family room.
If we consider the room as being part of the music reproduction system, then it is, by far, the most expensive part. Real estate is costly…