Another powered sub hook up question


I have a passive pre with only one set of outputs. I want to know if they're any options to hook up a Def. Tech. Supercube III powered sub. The easiest option is hooking the speaker wires to the sub, then hooking the speaker out to my main speakers. This utilizes the high pass filter built into the sub. This is option 1. Easy enough.

However the instructions with the sub say for more overall bass output using full range speakers, run the main speakers full range by hooking them up directly to the amp. (Option 2)

Does this mean I can hook the amp directly to my main speakers and sub at the same time? This doesn't sound right to me. Is there any danger to my amp (Edge G4) doing this? My main speakers are rated at 4 ohms and the sub from 4-8 ohms. Any advice greatly appreciated. Thanks to all.
If your sub has speaker level inputs then everything is fine. I run my subs just like this. The sub will draw a small amount of current from the amp to run its internal amp but not enough to matter. There is no danger to your amp. If the sub has only line level inputs then you have to go another way. I don't understand your proposed hook up. If you ran speaker wires to the sub you would be using the subs amp to drive the sub from signals from the main amp but if the main amp was not driving the main speakers where would the signal be coming from?
I am using a speaker level connection for my powered sub. The main outputs from the power amp are connected to the subwoofers speaker level input. Naturally, left and right output of power amp to left and right speaker input of subwoofer. The main speakers are now connected to the subwoofer speaker level output, left speaker to left output, right speaker to right output. My cable connection from the power amp out to the subwoofer speaker input is actually a 4ft pair of anticable speaker wires. The main speakers are connected to the subwoofer output with a 12ft pair of Anticables. I thought it was a good idea to use the same cables on the subwoofer and the main speakers. Prior to the anticables, I did the same thing with Kimber. This type of setup should work for you.