Bose 901 Series V along with Equalizer ...What else do I need?

The Bose 901 speakers require the use of a specific equalizer that is designed to optimize their performance. If you have a Bose 901 equalizer, you will need to connect it to your Lafayette 3500 receiver in order to properly use the speakers.
Here are the general steps for connecting the Bose 901 equalizer to your Lafayette 3500 receiver:

1. First, ensure that the power is turned off on both the receiver and the equalizer.
2. Locate the preamp output jacks on your Lafayette 3500 receiver. These will typically be labeled as "pre out" or "line out".
3. Connect a pair of RCA cables from the preamp output jacks on your receiver to the input jacks on your Bose 901 equalizer. These jacks are typically labeled as "preamp in" or "line in".
4. Next, connect another pair of RCA cables from the output jacks on your Bose 901 equalizer to the main amplifier input jacks on your receiver. These jacks are typically labeled as "main in".
5. Turn on your receiver and equalizer, and ensure that the volume levels are set to a low level before playing any music.
6. Set the Bose 901 equalizer to the "On" position, and adjust the various equalizer controls to your preferred settings.
7. Finally, play some music and adjust the volume levels as needed. You should notice a significant improvement in the sound quality of your Bose 901 speakers with the equalizer properly connected.

Note: It's important to use the Bose 901 equalizer specifically designed for the speakers. Using a different equalizer or not using any equalizer at all may result in poor sound quality or damage to the speakers.

The BOSE 901 equalizer will be inserted between your preamplifier and power amplifier, for more info please see here: https://deercreekaudio.com/resources#f467075b-ce37-49ea-b5f7-10e8eb2aa4f6

The setup is possible, but with several compromises. First off, to use the active equalizer, you'll need to insert this into one of the 2 channel AV channels limiting your listening with the equalizer to stereo only. The acoustimass subwoofer acts a driver/power regulator for the little cube speakers. It probably will not be able to drive the 901s at the correct level when attached to the Acoustimass unit as front left/right speakers. You could try running a dedicated set of speaker leads to the 901s which may work and still allow surround sound, but you'll lose the equalization capability on the 901s.

The key to running the Bose 901s is to have the equalizer inserted into the tape monitor loop. Most 'old school' stereo receivers have tape monitor inputs. On an AV receiver, the VCR or CD analog inputs/outputs could be used but you will be limiting your listening to stereo sources. Please be aware that some AV receivers will not allow you to select different audio and video sources. The Marantz NR15xx, SRx004 receivers are pretty flexible, and allow you to pair up a component audio input with an HDMI (or other) video input. (No surround sound in this type of setup...)

It sounds like you've read one of my many posts on 901 deployment in the AV world.

Functionally, what is the difference between one amp with 'x' channels or 'x' mono amps? Nothing. Pre-outs don't know or care what else an external amp does.

According to this link http://www.ecoustics.com/electronics/products/new/642968.html those amps are 2- and 5-channel, respectively.

There was a time when I had two bridged-mono Carver Cube atmps (at a real 400 watts) pushing one 901 each but that was big time overkill.

I now use a Carver AV-406 (functionally the same as your MM7055) with the 901 EQ in between the AV Receiver's front pre-outs and two 110-watt channels. Other channels on the AV-406 pull subwoofer and surround back duties. My AVR directly powers only the center and surround speakers.

The MM7025 would work for you.

If you are using the Bose Equalizer to optimize the sound of the 901s by going through either a tape loop or a pre-out/main-in loop, then the only way to do this without also equalizing the sound sent to the second set of speakers is to manufacture a "zone-2" output from the Luxman.
You'd probably need to split the send from the Luxman's pre-out before the EQ and send it to a second power amplifier for the second pair of speakers (if you want the Luxman's volume knob to control both speaker sets) or from a tape level output (if you wanted independent volume controls for the two speaker sets.
The whole EQ thing made 901s difficult to use on vintage equipment with only one "zone" audio outputs. Unless you want to use the Bose EQ on the second set, too, you can't do it satisfactorily without adding another stereo amplifier. But, go ahead and try it, you might find that you actually like the odd EQ that the 901s EQ gives to the second pair!
If it were my decision, I probably would not do it without a second amp, but it's all about what you like, my opinions really don't matter in your house, do they?
Have fun

As far as I know, any equalizer will work. There is a guy on here that might know more about them, but I never had the Bose equalizer and I have Bose speakers for 35 years. The guy at the electronic store back then sold us a little equalizer at first, we graduated from that a long time ago, and now on the 3rd or 4th one. No problem, works great, sounds better than ever. Hope this helps.

how do I hook up the bose 901 EQ to a yamaha DSP3090??

Yes! When the Bose ~Steve901 first came out that was the amplifier of choice -like the McIntosh classic amps. The 901s have their own equalizer as that speaker system is a phased-array, 

i, trying to hook up a powered subwoofer to my hafler dh 110 and dh 500 running a bose 901 series v active equalizer and series v 901s any info would be appreciated