Input impedance for Adcom GFA 555?

Well, egg on my face, after getting down on my hands and knees and peering underneath what I called the RCA jack is actually just a binding post and there is a grounding symbol underneath it. Mystery solved!

Hey guys, I have a system up and running and so far I’m very pleased! Lots of tweaking left to do but I have a question right out of the shoot: I  have a grounding issue because I’m getting home from the sub. Step one in the owners manual is to ground the sub to either the main amp or preamp. Since I am I am bi-amping, I will ground it to the preamp. So…where is this the grounding connection on the 2WQ??I guess I’m being overly cautious - there is only one connection whose use is not clearly labeled so by process of elimination that must be it, but I’m just not sure. I would attach a photo but it’s not clear how to do that.

Thanks again!

OP: Ok, sealed then!

You might also want to look at the AM Acoustics room mode simulator.  Try to keep your speakers, subs and listening location out of the way of the bottom most room modes.

Thanks guys! Adcom is definitely still in business so that is a sound recommendation. As far as main speakers, I have Vandersteen 3A’s.

Greetings 

Per a Stereophile review of the GFA-555 they list it at 22K. 
Not sure if Adcom is still in business. It would be best to call them.

Joe Nies

For most solid state 50k to 25k is more common.

Try the low impedance setting. If you hear no change at all when using the crossover use the higher value.

Also, what are your main speakers?  If they are ported it may help to plug the port before configuring the sub.