A deeper more holographic soundstage.

OP, same quest here.  Was ok but things popped when I did what Millercarbon is suggesting. Symmetry in all dimensions to the inch, or quarter inch when possible.   Get a $39 Bosch laser measuring device.  I didn't get from your post what you've done to date so sorry if you've done this.  Unless or until you do this, its a fool's errand.  

Millercarbon is right about the EXACT angle necessary to position speakers.... That is mandatory...

Happy New Year....

Dchang05,  isn't this how you describe your new system?

I purchased BHK preamp, M1200, and P15 together three weeks ago. The first week they sounded flat and dull, but now they are phenomenal.

So are they phenomenal or did you lose soundstage width and depth?

Your old tube amps had pretty high output impedance which could cause frequency anomalies and depending on your speakers you could have shelving of the highs with the 1200s. Odds are if you equalized frequency response your perception of soundstage would be more consistent.  Perhaps a better statement is that your amp, pre, DAC shouldn't impact sound stage (as intended) if they are neutral.

The deep wide former sound stage may have been artificial.

Twoleftears:  I agree with you. I have Ilumnia Magister speakers: Omniradial.1 meter from the wall  in 8-10°. Listeningposition in a “triangel”:only with that kind of speakers , you have a perfect 3-D sound. The chamber should also be “”echo-free” by using absorbent plates, if necessary. ( my system: CEC (cd-player), Metronome Technologie C6 (dac), Daniël Hertz  M6L ( preamp) and Wavac Md 805m ( monoblocks))

I read a lot of things written here as if they are gospel. I will give you my own experience.

 I have a holographic sense of space that reaches beyond my speakers and with excellent and focused imaging. I have substantial equipment between my speakers, and have no room treatment beyond an area rug and acoustic tiles in the ceiling. The room is built on a concrete pad, and thus the floating wood floor is firm. The speakers are ATC SCM35’s placed two feet from the wall and about 10 feet apart in a 20 by 20 foot room. I do not separate my cables, but I have a really excellent equipment rack of wood with steel points in steel cups separating each rack level. I do have a tube preamp, but I get the same sense of imaging depth with both a C-J tube amp and my tweaked-up, 45 year old Ampzilla, and whether I am streaming or playing vinyl.

So, while room treatment may help and equipment rack placement may help, you can get to this level of imaging without it.