That surprises me that it shuts down their totl in stereo mode or at all for that fact. My suggestion is get a 2 channel power amp, like the NAD C-270 (i have the C-370) and just hook that up to the recievers pre-amp outputs if it has them. The 270 runs about 600 bucks. OR sell your reciever and get a different one.
such as the NAD T762 reciever. it will run you about 1300

NAD T762
http://www.yawaonline.com/yawaonline/nadt7sursoun4.html

NAD C-270
http://www.yawaonline.com/yawaonline/nadc2powambr.html

the reason i reccomend NAD equipment is because first of all i own the c370 and its got alot of good clean power and sounds good with the axioms and because i know they offer alot of value for the money, and they are known for their power. And also YAWAonline is a good place to buy NAD online because they are authorized and they have good service and descent prices.