10agw +10agw=7agw? need some big Banana's

Math is correct, but only for solid core. YMMV with stranded. The largest banana plugs I saw on Parts Express is 14 to 8 gauge. They may fit, depending on the number/size of conductors making up the 10 gauge (individually they may be less that 10 solid).

I think the WBT-0645 will work,
https://www.musicdirect.com/connector-upgrades/wbt-0645-safety-banana
https://www.vhaudio.com/wbt-0645.pdf
Or using two stackable banana plug for each 10 awg wire,
https://www.parts-express.com/angled-locking-stacking-banana-plug-with-dual-set-screws-poly-shell-an...
If using existing spade, a spade to banana adapter will work too,
http://cardas.com/cab.php

Sorry about below.  I had spades on my mind I guess.
Try again....
Here you go.....

"need some big Banana's"

That's what she said.

levy03, I installed spades on mine.  Be careful - each cable consists of multiple insulated strands, but one of the strands is not solid.  It is stranded (many very thin strands).  I'm not sure why, and perhaps they changed design, but if you ever cut and strip do it carefully.

Here is one more...

thanks for the ideas to all. glad i posted.

mitch2...liked Douglas Connection.  never seen/heard of the site before. great stuff.  had a few nice options available. went with these......
https://douglasconnection.com/product/furutech-fp-200b-g-high-performance-banana-connector/

Kijanki4....agree/you're absolutely right about being careful. these cables are monsters with different shaped strands and lots of them. gonna take the above Furutech bananas to my local shop and have them put on right and re-wrapped. $25 or so is a small price to pay for the tedious task avoided and peace of mind that it was done correctly

should be done with this pita speaker cable rehab next week. spending $300 redoing all the tips seems (is probably) crazy but i really love these dam wires

cheers

Knukonceptz sells banana's that will accept 8 guage wire I have them and they really do others I tried that claimed to  didn't work.

There are new connectors from AQ that accommodate thicker gauge cables.  All their new speaker cables combine a separate treble and bass cable for bi-wiring.  If your dealer is an authorized AQ dealer he can order those for you. 

If it is a matter of success or failure, trim a few of the conductors. But, beware; forever you will know it and it will completely destroy any satisfaction you would have had, even if you upgrade $50K in gear.  ;) 

I agree Doug - a psychological barrier for sure but that is why even at times when I have really, really, wanted to trim a few, I always retwisted and reinserted the wire bundle just to get those last one or two uncooperative strands in with the rest of the team. 
There should be no reason for the OP to trim at all as the connectors in the links I provided are mostly huge.  I do not know about the Furutech bananas the OP ended up with but the Furez connectors are solid copper and have very large openings.  The bananas on the ebay link I posted look exactly like those I have previously purchased from Furez and if you go to the ebay store you will also find a silver plated version.   The Furez bananas had a small red or black foam insert inside of the connector barrel to resist deformation and help maintain a tight connection.
I make power cords using six, 10 awg, vintage Western Electric wires (2 wires each to pos, neg, and ground) into a Furutech plug/iec - without cutting the wires.  That can be tedious, but on big amps the result is very nice....sort of like turbocharging the amplifier yet maintaining a nice tone.

mitch, I didn't even bother to look at the connectors; just having fun. :) 

quick follow up......things did NOT turn out well. got my Furutech banana terminal and tried to have them installed. no go. the wires did fit into the connector (barely) but would not allow for the screws to set far enough in for the sleeve to slide down/over. really bummed!!
my local shop ended up getting/installing some more AQ banana's that did fit/work (again, barely). so i now have new AQ 500 series plugs all around. 

ordered the Furutech's above based on the 5mm spec they advertised. according to my math, that shoulda worked. it didn't. with the various types/shapes of wires AZ use's in the Santori shotguns, it was impossible to get them bundled up tight enough to allow the screw to set properly.  spent almost $500 in total to replace all the terminals/12 total, including professional install..... on 10 year old cables,??!.   don't even know for sure i'm gonna like them with the new setup?.

starting off by comparing them to some new, comparatively simple pure copper bi-wire cables from Schmitt (10 agw). will move on from there depending on what i hear.

no one told me there would math involved when i got into this hobby!! =)

That is too bad.  The Douglas folks are pretty good so maybe ask if you can return the Furutech connectors.  The 5mm ID specification clearly should have worked with your 7 awg wire, which would have a diameter of only about 3.7mm based on an awg chart.  The maximum specified diameter should have allowed for the set screws to be inserted far enough for the barrel to slide over the assembly.  I have personally used the copper Furez connectors I recommended (same as on the ebay link) with two runs of Western Electric NOS 10 awg wires, also a total of 7 awg, but they do not have an outer barrel so the covering is just heat shrink.