Need help with cable termination!

Not an answer to your question yet however if the two wires fit into the Vampire Banans, why did you switch to the Furez?
As far as I know, if you can't fit the two 12 gauge wires into your Furez Bananas, you could pear back the number of stranded wire until they fit, perhaps not an ideal solution. Or purchase a different brand of bananas such as: https://www.vhaudio.com/connectors-speaker.html#banana there are similar ones on eBay from other countries that sell for a lot less, but sound and work very well. What I like about them is the opening for the wire is large, but best of all there is a screw cap that allows you to tighten the bananas once they are inserted into your amp for secure contact. If you wanted to you could always add a bit of high-quality WBT silver solder.

Lak,

Thank you so much for your thoughtful response!

To answer your question about the Vampire plugs, the fact that they are a side-entry design is causing some major cable management problems at the back of my amp.  I have a Unison Research Nuovo, which has a nice bi-wiring option by having 8 rather than 4 speaker wire terminals.  Also, I should note that the 8 runs of wire are being used in conjunction with  a roller-block style isolation system on the amp.  This means that the side-entry design of the Vampires adds a lot of pull and strain on the roller block setup by tugging on the amp.  For these reasons, I feel that the rear-ported design  of the Furez plugs offers a cleaner approach and allows me to better use my Furutech cable lifts to manage the speaker cables at the back of the amp.

The funny thing is, that I got one or two of the wires to fit the Furez plugs on the first couple tries, but for the life of me, I don't know what twisting technique brought about success.  Could have been that length of these particular stripped ends hit the sweet spot.

Interesting also that Take Five Audio in Canada offers terminated Mogami wire in a true bi-wire configuration into slender multi-contact bananas, so I imagine that they have a workaround for what appears to be double the size of my current problem!  

The final though is that the Furez are crimp-style and hence very pliable, so I could look into enlarging the hole before adding the wire and crimping.

I had really terrible luck with Furutech. The plug material itself deforms easily and is a tad too small. With Focal speakers I never got a tight fit.

Instead I recommend WBT. use the sleeves method. Available from Parts Connexion.

Best,
E

Mental - Yes, I do know Doug and that's a good suggestion to contact him for advice.   He also made a custom speaker cable  configuration for me a couple years back with a thinner gauge of Mogami wire (2921 model). He does handle the Furez line, so if anyone knows how to terminate them, Doug surely does.

Erik -  I  know what you're saying about Furez connectors deforming themselves, as the plug bends rather easily, but they do fit snugly on my Unison amp.  On the speaker end, I think I'll leave the Vampire bananas, as my Spendors have a screw mount binding post and the side-entry design of the Vampire bananas allows me better access above and below the speaker binding posts.

Erik, when you mention the WBT crimp sleeve technique, is the idea to crush the sleeve around the wire ends and then insert into the banana plug or rather to inset directly into the amp's speaker terminal? 

Update: Looking further at the various Furez banana options and the  spec sheets, it seems that the 48s are not the bananas with the largest opening that Furez offers.  The XL in the part name,TSTWP48XL, refers to the sleeve size and not the opening.  Furez has plain bananas (TSTSB60NP) without the sleeve covering that have an opening that's about 25% larger in diameter. That should do it.   What I need are rear-design bananas which claim they can handle 4awg wire.  My current Furez say 6awg (or two @ 12awg, but, that's unrealistic).   

Thanks anyone for their suggestions!