Do Banana Plug Adaptors Degrade SQ?

Maybe.

hardly at all, if you use em right (bfa style is excellent)

Monoprice bananas are excellent! I use 'em! I hear NO difference between brands! You can make your own bare wire-to-banana adapters with a few inches of some single-strand copper hook-up wire (18 - 22 awg). I have done this myself! NO effect upon SQ!

No. 

Maybe not.

But in case a one or two word answer isn't helpful (hint: it isn't), here's a deeper dive: https://youtu.be/HphbTOHtH8o

Bare wire works fine and has good surface area, don't over think it. 

No. I prefer them.

In theory I suppose everything de grades.  That said how great was your previous connection? How often did you open it and remake it with a clear wiping motion that cleans oxidation? Getting out of this minutia I can tell you that I can get absolutely superb sound with lots of connectors so long as they are tight and clean my two senses people worry about the wrong stuff

Not without soldering that I know of, that is what I do with short OCC wire, or one time with Kimber. An extensive search might turn up something, probably bigger and worse sounding

I’m using them on my setup running from a McIntosh MC2205 to a pair of large advents. Clear as a bell. 

This seems to be what you'd like, but I can't discover how it was achieved.

http://audioklassiks.de/wordpress/?p=2303

If you aren't comfortable soldering and opening equipment it might not be possible. Removing speakers to access the inside of a cabinet can be distressing and extreme care needs to be taken not to damage delicate cones, so I get you concern, particularly if slotted screws were used.

Having said that, it is entirely possible by encasing the screw head with your thumb and forefinger to keep the screwdriver in contact with the screw, and using a very long screwdriver, which helps keep it perfectly perpendicular. Just use as little force as is necessary to keep the screwdriver in contact with the screw and slowly rotate the screwdriver. Gently and slowly is the key, one screw at a time. If your muscles are up to it, consider taking a few goes for each screw, so there are no mishaps.

I have used the cheap banana to spade adapters from Amazon and I thought they were fine until I got a set of XOX Spade Adapters from Black Cat Cable.  
The XOX adapters not only worked better and had a better construction, they sounded essentially perfect as if there was no adapter attached.  I use them to this day and will until the day I depart this life.
Just my 2 Cents worth.

The JBL L65 looks like it has recessed binding posts on a 45° angle.

I have a pair of 4412As with likely the same arrangement.  It may be different in the case of the L65, but I doubt it.


JBL thoughtfully made the binding post spacing that matches a Pomona Electronics 1330 or 4892 dual banana plug.  That's what I've used for years.  Makes connecting your speaker cables a snap, even in the dark.


https://www.pomonaelectronics.com/products/banana-plugs-jacks-and-hardware/banana-plugs-and-jacks

And specifically the 1330:

https://www.pomonaelectronics.com/sites/default/files/d1330_100.pdf

The 4892 is the same as the 1330 except it has a wire strain relief molded in the grip.  If you want gold plated contacts, use the 4898:

https://www.pomonaelectronics.com/sites/default/files/d_MDP-4892-4898_102_7.pdf

The 1330/4892 series banana plugs are readily available from the usual suspects, Allied Electronics, Mouser, Digikey, Arrow, etc., etc.

I have the audioquest wel speaker wire and I have bananas.  I doubt they would have bananas on their top of the line if they sounded audibly worse.

Bananas into 5way posts have always seemed a 'gold standard' for 'better' equipment, speakers.....

A better move would be optical, to duck the whole issue of cables and IC's, and how they can 'improve' or ruin response..

...although I can also already hear the claims of 'our optics are better than X, Q, or whoever's fibre IC....

So maybe we're better off just 'standing still'...*L*

I doubt either either Will Occur.....but, on the other hand, Could....

Of course, this is 'digital realm' stuff....

Anything in a signal path changes it.

Not for me when I had 3 alternate amps going: 3 sets of color coded speaker wires, all with separate WBT Banana Plugs (you manually tighten them when you insert them). I put a 6 ft pigtail with female from the speakers that I could reach without bending! A couple years of comparative listening, myself and with friends.

http://www.wbtusa.com/pages/0645m.html

In the past I used some Radio Shack self-tightening type (fixed pair which maintains spacing). The knurled ends are for tightening the speaker wire, once, then it’s simply push in/pull out. This type, the speaker wire connection  to the plug can mysteriously loosen, the WBT uses a pair of allen key set screws, the wire connection never loosened. They are well worth the price.

https://www.radioshack.com/products/gp-dual-banana?variant=20332018373&gclid=CjwKCAjw7diEBhB-Eiw...

This is when EVERYONE picked LP over CD; R2R tape over LP; Tubes over SS. I had a Pair of Fisher 80z Tube Mono Blocks (30 wpc); Fisher 500C Tube Receiver (30 wpc); McIntosh SS MC2250 (250 wpc).

You made me think, I still have those cables, Just for fun I’m gonna compare my Fisher 80z Tube Mono Blocks with my ’new to me’ Luxman SQ-N150 10 wpc Integrated Tube Amp that arrived yesterday. I listened with a friend for 3 hrs last night, that little Luxman is amazing. I’ve never used less than 30 wpc here. I knew it was small, but when you take it out of the box, it’s small (but heavy). Beautifully built (I didn’t look inside).

Some old JBL speakers of my acquaintance use spring loaded button style posts that take at most 14 ga. wire.  These adapters from Parts Express allow you to attach any banana plug.  Adding a few inches of solid 18 ga. won't hurt...you should see the wire inside the speaker!
https://www.parts-express.com/Lil-Piggies-Binding-Posts-to-Lead-Wire-Adapter-Set-Red-and-B-091-1262

Hello,
There is not a huge issue running bare wire as long as you tin the ends. Depending on how resolving your system is you can get arcs from stranded wire. 
My favorite banana adapters are the Straightwire BANAUNV. It will convert a spade or bare wire to bananas. My favorite is they utilize the Z banana. This insures a tight fit and a lot of surface contact. https://www.straightwire.com/mobile/connectors.php
Scroll down to see the under the connector list. If you are in the Chicagoland area this store is a dealer:
https://holmaudio.com/straight-wire/
Another solution is buy Pre- made Straightwire  cables and unsolder one of the ends. They are a great value product! I wish I could demo cables but I am in the process upgrading my system so there is no point until I get my electronics first. 

Update to what I posted earlier.
I found the service data for the JBL L65 speaker. 

L65s do use a different speaker binding post arrangement then the 43xx/44xx series.  Original L65 binding posts are JBL part number 56130 (black), 56131 (red).

I can't tell for sure, but it looks as though the original binding posts are shorter and smaller diameter.  The threaded post looks hollow.  If that is the what you find, measure the internal diameter of the threaded post.

If you find it to be around 1/8" or 3mm, then you can use a "miniature" banana plug like the 2944.

https://www.pomonaelectronics.com/products/hardware/miniature-banana-plug-solderless

I use bananas from KLE Innovations - they are the very best I have found to date and make a noticeable improvements in dynamics, clarity details and image.

But they are a little more fragile than most others, so if you cables are heavy (larger than 10 gauge) and the binding posts are further than 20" off the ground th bananas may work loose

I also found these bananas to perform better than bare wire or silver plated copper spade connectors

regards

No.

Just like any other connector type, they are just another connector.  Unless they are grossly underrated for the job they are assigned to, or corroded to the point where they do not conduct properly, all conductors are about the same.

Yes, but it depends on the quality. The quality we have now is much better than what was available in the past but even so, this is worth a read:http://www.tempoelectric.com/Wire_and_Cable_Facts.pdf

For what it's worth, I prefer bananas for their ease of use and the solid and stable connection I get.

All the best,
Nonoise

Any discussion on differences of connectors (i.e. "which is better") apart from being the same brand/manufacturer is a waste of time. The only proper assessment is with the same brand/model of cables with different connectors. I that context, spades are typically superior, but one would have to conduct a comparison with any given set. Adapters typically degrade. Anyone who dismisses such factors is obviously not seeking extreme sound quality.

In the scheme of the entirety of system building, adapters are just one of the many variables that influence the system. It is not absolutely necessary to have optimized terminations, but it will lessen the sound quality not to have them. Read my review of the Iconoclast Cables at Dagogo.com, wherein I comment on the difference between their banana and spade terminations. My finding was in line with the company’s position on the sound of each.