Fritzenheimer
After $10,000 to $15,000, it is all diminishing returns until the room is treated.....IMO. The room is easily the equivalent to going next tier on: preamp, amp, DAC, transport, and cables.
I was NEVER a room treatment believer until about 2 years ago, when I took my current gear over to my friend Patrick's house after he had just had his room treated with GIK solutions. Similar size room, similar power upgrades, only difference was a well though out treated room.
My gear I used at the time was about a $19,000 set (preamp, amp, DAC, Streamer, Speakers), but in the several days of listening in Patrick's treated room and playing with speaker placement; I would have thought it was a completely new system......maybe $35,000.
That taught me enough, that I embarked on my own project. I am finishing my basement by adding an extra bedroom, bathroom, and completely from scratch dedicated audio room......should be completed and ready to install gear by beginning of June. Giddy up!