VERY LOW VOLUME FROM SORROUND SPEEKERs

I've experienced the same thing on my TX-SR605. Some NFL games have too much of a surround mix, and it makes the center channel volume seem low. Also, some movies don't seem to be mixed well. Try the ProLogic 2x Movie setting. Also, you can manually adjust the center volume if necessary.

Batteries in the remote dying?

The chances are that you have selected an incorrect sound setting or not switched it on, for the HDMI you are using. With Onkyo receivers each connection will have it own settings for video and sound. You just need to look in the manual as to how to select the settings.

After a long effort searching on Google, I found a solution. There is a Late night setting on the remote that limits the loud sounds scenes so it is not much loader than the dialog. Works great, I can't believe I never notice the button before.

On your remote control, first press the "RECEIVER" button followed by the "SETUP" button.

Here is a link to the user manual (bottom right corner of page): http://www.eu.onkyo.com/products/TX-SR605.html

From page 70 onwards it is explained how to set up the speaker levels.

Alternatively you could of course adjust the volume on the subwoofer itself. Most (active) subwoofers nowadays offer an output volume adjustment.

Good luck.

Does any good sound come through headphones, if you plug any in?

Yes it is. I have the 705. My room mate has the 605. Both AVR's will not have appreciable volume until 50 on the dial.
The dial in not linear. I don't know of anyone who has plotted the scaling of the volume control yet.
I have found much useful user info on avsforum.com. Owners post Q&A based on experiences.
Search the forum for "official onkyo TX-SR605" thread.
Some comparable info may also be found under the "official onkyo TX-SR705".

It's the receiver, same prob here. The level of bass through the sub is negligible too. So my guess is it's either related to the crossover or the passthrough in general.
Looking for a missetting or workaround.

Channel level output can be adjusted in the menu if you have the remote. Set the rear channel level volume higher and the fronts lower if need be, and then turn up the volume. Enjoy!