Sibilant output from Pioneer VSX 1018 AH-S

Have you solved ???? Thanks .. I have the same problem

Did you remember to remove the shorting link on the MA BR5 speaker terminal ..When you biwire the speakers you should remember to loosen the speaker terminal nuts and remove the shorting link plate between the HF and the LF terminals or you will short the amplifiers two channels together through the link. And modern amplifiers will take a lot of abuse at low volumes but at high volumes the protection circuit will turn off the device.

You speakers are out of phase. Check to see if the polarity is correct on the receiver and the speaker. Positive (red) with positive, negative with negative (black). Also check the impedance of the speaker, it should be located on the back of the speaker measured in ohms. Make sure that your receiver matches the impedance of your speaker. You can find this in the settings of the receiver.

Check if your KuroLink is on or off. There are a lot of problems that users have been having with the KuroLink on. Since you have a Pioneer display, KuroLink might help in switching both the receiver and the display on and off together, but my advice to you would be play around with the settings (in your case, especially KuroLink). Also remember, the KuroLink is on by default i.e. if you've never changed this setting, it probably is on.
Hope this solution works, else check out the Official Thread on Pioneer VSX 1019 AH-K on avsforum. There are a lot of helpful people out there.

The DVI output usually transmits only video (I'm almost 90% sure about this). It would be better if you did not use the DVI to HDMI cable. Receivers and displays can be very picky when it comes to using HDMI. Your Motorola DSR505 has other output options on its rear. I would suggest using the Component out for video (the 3 outputs colored green, blue and red) and either an optical or coaxial for the audio. The Pioneer VSX 1019 AH-K has the required inputs. Of course, you would require new component and coaxial/optical cables to do the job.
Hope this helps. If you're still in a tangle, you can consult the Official Thread on the Pioneer VSX 1019 AH-K on avsforum. There are a lot of helpful people out there.

I guess you don't have the owner's manual for this?
You can get it here:
MS907 Subwoofer manual
The manual contains connection info.

I think you're making this way more complex than it is.

This unit should have no trouble with any reputable speaker. Don't read too much into short term impedance readings as long as you run only one speaker per channel. Every speaker has a dip somewhere in its frequency range and the Pioneer will probably protect itself and the speaker should impedance or current get too out of whack. This is a high end unit and has plenty of clean power to feed any speakers out there.

I'd buy it if I didn't already have a 6-year old predecessor (VSX-T36TX) that I paid twice as much for and has only 5 amplified channels, less features and lower power output. ;-(

Good luck and happy listening!

is it the correct mains from reciever?

It's probably just a setting issue. Either on the TV or Receiver. You need to check that it is sending the right audio signals to your devices.

Be sure you have proper impedance with both sets connected. Some units have a selector switch in the back of the receiver to set the proper bias. ...accordianman