Time to upgrade DACs

As others have mentioned, swapping the DAC isn't going to get you 'bigger, fuller sound'. Having said that, I'd consider the RME ADI-2 FS as a DAC because it has a 'loudness' feature that may provide the bass you're looking for at lower volume levels.

The SF speakers are probably the weak link in your chain. I had a single REL T7 and was pretty happy with its performance. If anything, I'd expect dual T9i's to fill in the low end pretty well.

Based on your desire to add 'fullness' and good imaging, what you probably want is a tube preamp. Tubes will add warmth (fullness) and increase the image size. However, images may be more vague with less pinpoint accuracy than an all solid state signal chain can provide.

In regards to imaging, perhaps consider speakers with ribbon tweeters. IMHO good ribbons image far better than any dome tweeters I've heard.

Also, is it simply a lack of bass that you're missing or does your current setup simply lack warmth? What setup were you running in the past that makes you think your current system lacks fullness? Could it be your current system is simply more honest than what you were previously used to an you actually prefer a system that shelves the high frequencies?

You are in "upgrade bug".

But 2500$ will not make huge difference in the sound.

Your SF speaker is still good.

How about getting Schitt Freya+ in front of your SS amps.

It will give nice warmth and more 3D soundstage.

You can also have fun through tube rolling.

Nice vt231 tubes can be had around 100$ from Ebay.

I am having lot of fun through Raytheon vt231 that cost me 65$ through Ebay auction.

"I left my heart in San Francisco" sounds realistic through tube pre in the chain.

Thomas

Sounds like you’re after larger scale and more impactful dynamics while maintaining excellent imaging. If that’s the case I think upgrading speakers makes the most sense as the GPs are on the small side and physics matter. Underwood HiFi is selling their new LSA 20 Statement speakers normally $7k/pr. for only $3999/pr. for a limited time, and they offer a 30-day trial period. If you don’t mind used, there’s a nice pair of Nola KOs for sale for $4500 ($12k retail) that with their multiple dipole drivers will yield a large soundstage with great dynamics and excellent imaging. Either of these would likely be outstanding choices. Best of luck.

i vote with others - speakers, and reclocker

In a room like yours, a side firing woofer and the right tweeter can do some extraordinary things.  The Scansonic MB-3.5B could be a pretty awesome speaker for you.  I first listened to them in a room that is about 15' x 25' with 15' ceilings. 

Placement is critical.  You would want to have them 8-9' apart and a solid 2' of space behind them.  That will leave 3-3.5' to the side of either speaker and your walls are treated.  

The scansonics have "raidho DNA" and regardless of what you think of Raidho's pricing, the tweeter they put in these speakers is unreal.  If you are looking for imaging and an extraordinary, three dimensional soundstage...and you have the right room, nothing beats Scansonic and Raidho.

The tough part for most people is the right room.   When you get the placement right, when the soundstage comes together it is immersive with the best imaging I have heard short of my own speakers.  

PM me if you are interested.  I am an authorized scansonic dealer and would even take your speakers on trade to make it super easy for you to upgrade.  Would need to talk condition but a very healthy trade allowance (~$1500) could make it an interesting option for you.  

I could also work with you on a Chord Qutest as a potential solution for your DAC.  Chord's to me have a more natural sound than traditional chip DACs.