Integrating a subwoofer

At least try 40hz. You cannot go by specs, it’s actual performance in that particular space. ’Real’ bass extension takes more than a single 10".

I think even 40hz crossover is too low, my subs (1 office with smaller wharfdales, 1 home theater with dbx 100’s) both do better at 80hz.

Office, I just add enough to keep the system from sounding ’small’. Only aware of it when I turn it off.

Home Theater, it’s to give some ’Dinosaur Stomp’, i.e. Jurassic Park, Black Hawk Down, not for music extension, the dbx soundfield 100’s do well enough on their own.

If you buy an inexpensive sound meter, it will give you good info. It doesn’t need to be perfectly calibrated, just shows output of specific frequencies relative to other frequencies. This one, on a tripod, ear height, listening position helped me a lot

this test cd has separate tracks for each frequency, and they are 1 minute long (longer than needed, but not too annoyingly short).

Lanx, you said the Parasound has the high pass filter? That cuts the bass to your Warfedales. Set the sub woofer to 40 Hz and the Parasound to 40 Hz.

Hey,

Make sure you are using the right place to hook up the sub.  If it's a processor loop or tape loop it is not the right place.

Next, your sub should have a high and low pass filter, so if you take the output from it to your amp you should reap the benefits.

If your main speakers are proted, seal them by plugging the holes in the back with unneeded t-shirts or socks.  You don't ahve to fill them, just plug them tight. 

Otherwise, if it was me I'd use a miniDSP to do this all, along with the right measurement software. :)

the subwoofer (connected through loop out)

This is your problem. What you want is pre-out or sub out. Loop is fixed line level. Essentially a bypass, it gives no volume control over the sub. Because of this it is simply playing way too loud.

Your amp does not have pre or sub out. The solution is a $20 Line Out Converter. You might be able to find one at Parts Express for even less. Don't pay more, it does no good. Connect the LOC to your speaker terminals on the amp, then connect your RCA interconnects from the LOC to the sub. 

Thank you all for the advises and corrections. While waiting for the LOC to arrive, I will go over these suggestions before devoting to a DSP. Also, I replace the softer rubber feet with the anti-vibration isolation pads that was used for washer and it helps.

Again, thank you all for your inputs, especially the correction and suggestion of line out converter (LOC) from millercarbon. My sub finally comes alive and is even better than before with my Cambridge integrated amp when connecting to preamp out. Much of refinement now is also attributable to the HPF on my parasound, where I still set it at 20 hz. I found at 20 hz the bass from subwoofer is more weighty and still controlled. At 40 hz, the low end lacks weight/extension and not as dynamic. Also, the sweet spot of crossover on my subwoofer is between 60 hz and 70 hz. Beyond 70 hz, the mid-bass starts sounding a bit too much boosted. I was never aware Einstein is also an audiophile genius.