Expert Pro sound quality

[Celts88]

I just hooked up my second 250pro as a slave.
I had received my first upgraded unit about couple of weeks ago and I thought it was clear winner against 400expert. I refrained from posting the impressions here because I wanted the unit to burn in for a week or two. Few folks here have already described the improved areas like bass control, deeper bass, wide and 3D soundstage, higher resolution, realism etc. So, I wasn't sure what would 1000pro would bring to the table. I would have been perfectly happy with a single 250pro. However, I'm noticing the same improvements a couple of notches higher than the single unit.  I was not expecting this much improvement with the additional unit. I'm not sure if my mind is playing some trick or am I a victim of some kind of a bias. The specs for dual mono are clearly superior in all respect and looks like they are delivering on those specs.
PS - My speakers sensitivity is 88.5db, so they are not really hard to drive either.

sam1000

My 2nd D-P is in France at the moment being upgraded, and when it returns will try and use it for the first couple of weeks as a single 250Pro (same as what I'm doing at the moment with my 1st upgraded D-P). Hoping to withstand the urge to hook it up in a 1000Pro set-up until it's been properly burned in. My 1st unit will have had 3-4 weeks by the time I get it back and hope to do the same run in time before going Mono (can I withstand the urge to hook-up both, only time will tell).

I suppose one benefit of my madness will be that I can then compare what a burned in 250Pro sounds against an new 250Pro. Also when I do eventually hook both up as a 1000Pro set-up I will get the same upgrade feeling as you Sam. At the moment I really don't know what the 1000Pro will give over a single 250Pro as it sounds great as is, so will be eager to hear the difference.