I bought a 990/7500 combo that I've been installing in my system in stages, so I could get a feel for how each component sounded.

The first thing I did was to listen to my 1050 for one last time on a range of music and movies. Then I connected the 7500 to the 1050's Pre-outs and listened to the same material.

Wow.

There were dramatic improvements in a whole bunch of categories.
- Bass was much tighter controlled, with better tonal accuracy and better definition of leading and trailing edges
- Midrange was smoother
- Highs were clearer, more detailed, and more airy. Sibilence was cut dramatically.
- Overall congestion was cleared up.
- Better imaging, much clearer definition of each instrument in space.
- More musical and rhythmic, which I'm thinking is due to getting the harmonics right.

All in all, if you are thinking of using a 1050 as the front end to a 7500, run, don't walk!

I'll post some 990 thoughts in that forum after another listening/tuning session.