Possible impedance matching issue with subwoofer?

Koestner, thanks.

Grannyring, Koestner makes a very important point about using a fully balanced amp with a sub, and your Aesthetix Atlas is indeed fully balanced. The negative speaker-level input of the sub should be connected to a ground point on the amp, and NOT to either of the amp's negative output terminals (which put out signals, as opposed to being grounded). Connecting the negative speaker-level input of the sub to one of the amp's negative output terminals could short the signal on that terminal to ground, assuming the amp and the sub both have three-prong power plugs, and depending on their internal grounding configuration.

A suitable ground point will often (but not always) be a chassis screw. You can verify that by using your multimeter to check for continuity between a chassis screw and either the ground sleeve of an rca connector or pin 1 of an xlr connector (while nothing is connected to the amp).

Concerning the input impedance of the amp, according to the manual it is an extremely high 530K, and is therefore insignificant with respect to the issues we have been discussing.

Regards,
-- Al

Al, the builder told me if the plate amp has the negative high level input grounded or in common with another connector (left minus connected to right minus, then I would need to do a special connection from the Atlas. Connect only one phase of each channel ( presemably the plus) to the high level input.

I will look at the back plates tonight.

Ha, ya a BIG hum is the last thing I need1

Ok, one last question so I can make my final decision. I am not sure I want to go the high level hook up route as I simply don't know how the plate amps are wired. Can't see anything as all the sub binding posts are hooked together on a circuit board with the traces hidden from view. I would have to take boards off etc and I don't want to do all that. My amp is fully balanced and I fear causing an issue due to the way the sub high level inputs may well be wired -Keiga KG 5150.

Bottom line. Is the line level hook up going to cause an issue in terms of impedance mismatch or not? Al comments as well as Nsgarch suggest I will not have an issue in terms of sound degregation. Here are the facts on my gear.

Preamps output impedance is 5k ohms
Plate amps input impedance is 22k ohms
My stereo Atlas amp has an input impedance of 470k ohms
My sub cable is very, very low capacitance -Al referred to it above and they 10 feet long. I run two subs.
My ic's between the pre and amp are 3 feet long

While the music sounds good I do wonder if I am rolling off in the bass area and possibly compromising the sound of my main speakers. Again, both Al and Nsgarch seem to suggest no issue. But some other comments suggest otherwise? I would buy a Buson buffer to place between my pre and subs if that is deemed as best. I understand that such a buffer would reduce what the subs see as output impedance down to under 600 ohms and perhaps as low as 100 ohms.

I would rather not spend the money if there is nothing here to be concerned with. I set my subs to play 40 hertz and below only. Since I have 2 I set the volume very low - near the minimum really.

What do you expert say.