Unless you have a properly set up listening room and access to some decent quality room calibration system, you will need to depend on your ears + test tones or the auto calibration provided by your AVR. In my experience, the calibration of an AVR makes a huge difference in the quality of surround sound reproduction.
For home theater systems installed in the regular living room or bedroom, it is very important to have a good calibration of the system to get the optimum audio quality.
The Denon 1911 comes with Audyssey MultiEQ, while Onkyo 608/609 comes with Audyssey 2EQ. The Pioneer 920k comes with pioneer's own MCACC. Of these 3, the Audyssey MultiEQ found on the Denon 1911 is the best out of these technologies, Pioneer's MCACC and Audyssey 2EQ found on the Onkyo systems are by comparison very limited in what they can achieve.
I would very strongly recommend a AVR with Audyssey MultiEQ or better auto calibration system to anyone looking at investing in a new HT setup. Do not go by how the systems sound at an AV dealer's demo room as those have very well done acoustic treatment. You also can not see the difference made by sophisticated auto calibration systems like Audyssey Multi EQ in most demo rooms, but when you compare the Audyssey calibration to even good quality calibration done using other techniques in a normal bedroom/living room, the difference is pretty huge.
-- no1lives4ever