What to upgrade?

Looks like a good amp and nice speakers. You probably just need to add a little "muscle" in that larger sized loft to retain good dynamics at higher volume.

If sound is good but dynamics lacking at higher volume, I would consider adding a pair of good powered subs. That's the easiest way to just throw some more power and air pressure at the problem. Crossing over to subs for low bass will also take load of the monitors and allow them to do better as well at higher volumes.

No doubt room acoustics in a loft can be tricky. Might wreck havoc on soundstage and clarity with perceived dynamics more the victim.

DEfinitely always a good idea to assess and get a handle on teh room acoustics before making a major change. That's often the biggest determining factor regarding what will or will not work. Good sound from gear heard elsewhere may not matter much.

The sub idea might still be the effective boost needed. Placement options with separate subs to compensate for room acoustics might be easier than just replacing with all self contained larger speakers. Corssed over correctly, existing amp should be able to perform more optimally as well at higher volumes with low bass offloaded.

Take a look at some of the audiokinesis Planetarium speaker systems that leverage up to 4 separate subs to help compensate for room acoustics. This might be a fantastic approach to consider in your case. I have not heard these but love the innovative approach and thought processes that go into Duke's stuff to wean out performance for reasonable cost.

Rover,

If bass levels and dynamics are good at higher volume, and all is well at lower volumes, then indeed likely room acoustics, possible treatments, speaker placement are the things to look at. Switching gear alone may accomplish little or nothing until these fundamentals are addressed.

To what extent have you played with what you have to get things optimized? Definitely do that first. Nothing wrong with what you have I could determine as described to prevent that.

Is there echo in the room when you speak? That's a good test to determince how lively room might be and how sound echoes within. A lively loft with lots of echo might be a difficult beast to tame fully unfortunately, but I'd be willing to bet playing around with things a bit might help significantly.

I read your speakers are rear ported.

First thing I would try is move both speakers 2-3 feet out away from walls minimum, more if possible and play around with different locations and see what that does, especially if rear ported. Bass may be affected negatively or not, but other current reported problem areas like detail and imaging/soundstage should improve. Adding subs if needed at that point might help.

Use a good mono recording and make sure speakers are close enough to produce a solid center image from your prime listening position or preferred sweet spot., not too far apart as to leave sound muddled and spread out with no center focus. Then try some stereo recordings and see what happens then.

You can also try toeing speakers in or out as well along with placement to help tune things. Might require a lot of experimentation to determine what sounds best at your preferred listening position.

I would try a position with speakers well out from nearby walls so that distance sound reflected of any nearby rear or side wall at each primary reflection point travels from speaker to your ears at your primary listening position or preferred sweet spot is at least twice that of sound that reaches you directly from speakers. This will help address timing issues between direct and reflected sound that will muddy the detail if not within certain tolerances.

If within the tolerances, as determined by relative distances direct and reflected sound travels to your ears, 3-D soundstaging and imaging and associated detail will improve. Try that first and tweak accordingly from there to fine tune.

"Interesting part is the further I moved the speaker in the corner out the bass became muddy/boomy."

When you listen, is your focus on the speakers, or the sound in the room?

If the first, bass might be perceived as more muddy with speakers away from walls as imaging detaches from physical location of speakers somewhat, but may sound more like live music if your focus is more on how the room sounds with the speakers playing.

Also you could certainly be getting bass resonances in certain locations, but those probably would change somewhat as actual location changes, and not necessarily on relation to distance from wall.

If two much bass, try loosely obstructing the ports for comparision, using a very loosely rolled up low density fabric cloth, or maybe try foam port plugs as an option. loosely rolled up socks will even make a difference and might help.

Experimenting with ICs is another option that can make big differences in bass performance and a lot cheaper than switching main components. With my gear, I use MIT Terminator ICs for more bass when needed, but prefer DNM Reson ICs for good balance top to bottom with coherent midrange. Either can be had for not much, particularly if used.

Some very basic power conditioning like a simple monster power strip to source and maybe pre-amp (not power amp) is another tweak that can often help with cleaner bass.

Myself, I would not change any major gear until I had what I have dialed in first as best as possible. That helps to identify what might work best from there better if further changes are still needed.

Unfortunately, I have not heard your stuff, but on paper, the components seem of good quality and well matched in general for good performance. That's a very good place to be to start prior to experimenting with these kinds of easier and less expensive tweaks to get things really tuned in, which often makes all the difference in the world.

Panels will usually help in a lively room. Panels should go at primary reflection points on wall based on speaker location and primary listening position. Distance from speaker to closest primary reflection point on the wall will dictate magnitude of the benefit, add one at a time, speaker closest to primary wall reflection point first for greatest benefit, wall can be side and/or rear. On side wall will generally reduce width of soundstage, rear wall reduce the depth. Particularly useful to reduce early reflections that smear detail if speakers are too close to the wall, usually less than a couple feet. Moving speakers further away from wall has same effect. I would determine the best speaker location first before applying any panels as needed from there because that and primary listening position or positions will determine the best locations to apply.

Thicker, more padded, household white items are easy and cheap tests to try just to see/hear if any difference at all before investing in panels. Good idea!

If effect is too much, try thinner quilt or reduce surface area covered as needed. Lots of easy household ways to absorb sound without specialized panels, as long as the wife approves. Relocating cushioned chairs or any soft asound absorbent item into the line of fire direct or reflected as well can also help "shape" the sound.