The STA-90 is very well liked by many.
I have one, and I consider it a keeper.
I like to compare mine to my Sansui 771 because it is from a similar time, in a similar segment of the market, and it is also styled quite similarly.
It compares very favorably.
However, I don't know if it is the way the volume control scales or what, but the STA-90 feels significantly more powerful than the 771.
It's not the Shack's flashiest receiver by any means; I think that the 771 is prettier, but it has a great sound and feel to it.
I like them both, but the market likes the Sansui more.
I have seen a couple go locally here on Craiglist for about half what the 771 goes for.
That's not a complaint.
They are simply a bargain if you can find a good one.
I used it in my living room system for about a year, and I was quite content with it until the tuner went wonky.
It awaits tuner maintenance presently.