One sub, a two channel system ,one HT reciever ??

When you use the line level in and out you are using the crossover and rolling your main speakers off at the subs crossover point.

On some equipment this can be a limitation yes. However, I think there are preamps out there that allow you to have control over each speaker individually so the sub can be crossed over or not and the speakers can be crossed over of not.

I'd look into the Anthem D1 or D2 if you want a high quality HT preamp with plenty of flexibility and that could also serve as a source for a decent two channel system or a two channel + sub system.

If your receiver folds the LFE channel into the mains when set to (large mains-no sub)....you can simply add something like the Paradigm X-30 crossover (around $100 used)into the system. (or any other good crossover on the market).

It would connect like this:

Two channel preamp>>Paradigm X-30>>Mains and sub. This sends the fullrange signal from the receiver, to the preamp. The preamp feeds it to the Paradigm crossover. The paradigm crossover filters the mains and subwoofer, or...just the subwoofer if you want to run the mains fullrange. (a second set of preamp outs required or splitter cable for this method).

I don't agree 100% with "Stanwal" on his second choice option being better....but don't really dis-agree 100% either.

Running the mains fullrange, is speaker dependent (the main speakers). The speaker level connection method assumes that the mains have a smooth low freq's response....many small ported designs are anything but. So....this method depends.

I also don't agree with this:

"The critical factor is not having to run your signal through the crossover".

If this were true (critical), we would all be using single driver speaker systems. Sometimes the gains, more than make up for any loss.

Note: My options also depend on a few things.

Dave

The idea behind not running the signal through a crossover is that it represents an additional degradation of the signal before it has been amplified, a degradation here can never be recovered. The crossover inside speakers represent a division of frequencies of an ALREADY AMPLIFIED signal and has far less effect on the sound. I am unfamiliar with multichannel systems and so don't understand the purpose of setting the crossover at 120hz but in operation no sub should EVER be set this high. Anything operating in that range is not a sub but a woofer. I run my subs as low as possible, I never have the sub crossover set above 40hz. In this way the output of the sub is nondirectional and it supplements the bass of the main speakers instead of interfering with it. Again I am writing from the perspective of 2 channel sound and of someone who uses subs with response below 20hz. The Nelson Reed was specified to do 120db at 20hz and extend to 16hz. The REL and HSU will go almost as low but not nearly as loud; they don't have 8 12" Volt drivers as the Nelson Reed.