I believe the specified configuration is in the manual for the amp.
http://mobile.jlaudio.com/pdfs/13192.pdf
If you follow that link and look at page 9/13 you can see the optimum configurations. In the 2nd section (stereo/bridged) you see:
1st Pair of Channels (Stereo): Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)
2nd Pair of Channels (Bridged)Bridged 8Ω: 150W x 1 (set to 34.6 V)