Wow!!!
With your feedback it makes me kinda want to use the KUBE. I am also set to large. I don't use the KUBE because I'm running balanced.

Might try unbal.
I'm sure we would all like to see a pic or several of your setup.
Enjoy!!!!
I can tell you do.

Pictures can happen. I didn't mention the custom stand for all the electronics...

Changing from balanced to unbalanced will not have any major effect on the sound. It won't even change the individual channel volume levels. The minor effect could be slightly increased noise, depending on quality of cables and length of run.

I'm actually running three channels balanced and two unbalanced between the 990 and 7500 (the KUBE only has unbalanced inputs/outputs).

Without the KUBE in the system I feel you should set your speaker size to small and cross at about 60 Hz. The Kefs have a pretty substantial rolloff below resonance without the KUBE and you're missing all the bass energy that is intended for the mains. Rather a shame, because with the KUBE they have bass extension and accuracy that few, if any, speakers can match even today.

The downside of using the KUBE is that the electronics inside are 20 years old and the power supply is not up to true audiophile standard. The KUBE will introduce some noise and you will lose a little bit of clarity on the mid and high frequencies.

It would be a very interesting exercise to measure the transfer function of the KUBE and design/build a replacement at today's performance standards. I wonder what it would do for the sound and whether there would be sufficient market for it to be worthwhile. Most sets of 107s that I see for sale are without the KUBE.

manahsm's reply makes sense.

The distance between 990 and 7700 is only 2 feet, so I could probably get away with unbalanced for the fronts and use a KUBE there. Might not add noise since the run is so short. OTOH your point about old electronics is a good one.

From an article by John Ross (original can be found at http://www.john-ross.net/pdfs/maghist.pdf )

My friend Delmar Benjamin is an air show pilot who is best known for his performances in the 1930s Gee Bee racer replica that was built by Steve Wolf and is now in Kermit Weeks’ Fantasy of Flight museum in Florida. Delmar has often and for many years said that for an air show airplane, there is no such thing as too much power. Air show pilot Jimmy Franklin (who was killed in a midair collision in Canada in June 2005) had always agreed with Delmar’s assessment.
Then, around 1998 or 1999, Jimmy mounted a military surplus jet engine with 3000 pounds of thrust between the landing gear legs of his 1937 Waco open cockpit biplane, which already had a 450 HP Pratt & Whitney Wasp Junior radial mounted on the firewall, producing over 1600 pounds of prop thrust.
After performing several test flights to make sure the biplane flew well with a jet engine mounted underneath the fuselage and that everything was working okay, Jimmy lit up both engines, gave the radial full throttle, and did a normal takeoff. He then pulled the airplane vertical and gave the jet engine full throttle as well.
With over 4600 pounds of combined thrust and an all-up flying weight of around 3000 pounds, the 60-year-old biplane had the highest thrust-to-weight ratio of any aircraft on the civilian registry, and it soon accelerated to its never-exceed design speed while going straight up. After easing off the throttles, leveling off, descending, and landing the aircraft, Jimmy got out of his plane, went to a phone, dialed the number of his old friend, and uttered three words:
“Delmar, we’re close.”


As far as having sufficient bass response goes, "I'm close."