Damn that thing has a lot of inputs on the back of it. See if you can find a copy of the owners manual, I have run 901's on several different types of AV receivers and they all have a provision to hook up an external equalizer, which is what the box is on the 901's so see if you can get the owners manual and track it down.
any luck yet rbh?
rbh, is there an EQ in? If so, run the pre-amp out, then to the EQ in, I have never seen a system that can't run the 901's, of course you also can just run the 901's off the speaker lead outs on the receiver, I have done this before and they will contour to the EQ in the receiver, you might drop Bose a note explaining your situation and I am sure they Engineers there will be able to come up with a solution for you, I have spoke with them many times, good group of people.
rbh are you saying without the bose eq your speakers will not function?doesnt sound right .id eliminate the bose eq all together and see what happens.im sure ive seen them running without the bose eq but its been a long time .
If you want the best sound, you are going to have to make the effort to learn that EQ in the Yamaha, so you can adjust for the best sound, my current set of 901's are not running through an EQ, they are straight speaker wires with a BIC subwoofer, it took a bit to get them to my sweet spot, but believe me it is possible.