I am currently running my new sonosub(shiva)with 2 monoblocks. Each VC is getting 125W each from 2 Soundstream THX cert monoblocks. When I try to run in parallel with just 1 block the first one seems to run fine but the other is going into standby. I'm assuming some type of short protection from low impedence because it jumps into standby in just a few seconds and isn't that hot. This thing is rated to run 4ohms so I'm confused. Does the Shiva drop well below 4ohms in parallel? Or is there something wrong with the amp? My LSPCAD model for the sub doesn't show anything below 4.4ohms in parallel until you get below 12hz or so but I'm not sure if this is reliable. As an after thought I'm probably going to look into a AVA250 but I'm wondering if I should get the blocks looked at because they are slated to run my new Studio 60s when I get them.