HELP Subwoofer connection, high level or low leve

The high level is best for a 2 channel audio system. You may actually have no choice depending on your preamp. The sub is therefore getting the same bass signal as your main speakers, which makes it much easier to get good integration of the sub with the rest of the system.

The low level is best for a multichannel system, including AC-3 or DTS Home Theater. Again, the sub-out on a HT decoder is going to be a low-level connection, so you really have no choice if you want the true Dolby Digital mix.

With the REL you can actually do both at the same time. If no subwoofer signal is received from the HT decoder or preamp, the sub will automatically use the high-level connections. There are separate settings for the high and low level connections, so you can set both to their respective best setting and forget it.

I believe this is all explained in the owners manual.

Rap....You may be correct, but it does not make sense to me.
In an Dolby or DTS HT situation basically the ".1" in the "5.1" is the bass. The sub is suppose to play this. Now if the sub is doing double duty by playing the ".1" channel and playing the bass of the main speaker at the same time, I would think it would confuse the sub and the result would not be clear detailed bass, but a bunch of mud.