Just unpacked and connected a shiny new pair of butter-creme passive MixCubes/Alesis RA-100 Power Amp.  First listen I had was a Transformers movie clip, then Sting CD "Brand New Day" and Aaron Neville "Warm Your Heart".  Definitely a different sound than my JBL's, but really warm and smooth.  I do like them.  Luckily, I fired up my most recent mix and sure enough some things were glaringly different from the reference material.  Hurray!...now onto some remixes.
 
Would there be any benefit in breaking these in for some hours with a 20 hz wave?

Yikes...after listening on these the JBL's feel completely void of mids...I guess it's not so much they don't have mids as the Cubes don't have the extended highs and lows.

That's kinda the whole idea. Taking the upper and lower extremes out of the picture lets you focus on the mids, which is really the most important range even though it's the low end we usually end up fretting over the most.
 
As for breaking them in, IMO speaker break-in is an urban myth. What little break-in they need has already been done by the manufacturer during QA. There has never been any evidence that breaking in speakers changes their physical characteristics in any measurable, much less audible, way.

It's getting more interesting as I'm listening to different material.  I just heard a pretty big plosive on a reference tune I'd not heard before.

Thanks for the input/review.
 
I'm thinking of getting a set of these some day.
 
But I might be going with the actives instead, as I don't have an amp to drive them.

Using two mix cubes to reproduce stereo is one way of using them. Make sure you also experience summing L+R signals at line level (even passively) and feeding a single power amp with that mono signal into one cube only. One cube is all you actually need. Then you get to experience what happens when several parts and too similar in sound and they end up all coming from the same place all lined up behind each other coming from a single point source speaker. Separation between those parts will be poor. You will need to do more to separate them more.
 
Single speaker is also good for mono compatibilty checks with wide stereo sounds such as from some synths. (or a very wide AB spaced pair of microphones picking up something very acoustic)

In quick listening last evening, it was more clear that the snare on a particular mix stuck out too much and I didn't like how the reverb on it sounded either.  I think I tend to make drums and bass too loud, and of course that limits how "loud" I can get my mix pretty quickly.  Overall the mix also sounded a little too dull as well.  I'm definitely looking forward to spending more time with them this evening.  Hopefully I'll learn to listen for the right things and turn the right knobs for the right reasons.

Donny it really sounds like you are getting into them and that is very good. I like to listen on the small speaker very quietly as well. It does not have to be that loud either. So many things start to stick out as being out of place. It is good to mix on them rather than switching back and forth to your mains. Setting vocal levels correctly in relation to the music is one of its great strengths. It helps balancing vocal harmonies too against the lead vocal.
 
Reverbs are harder to hear on the small speaker but I have found that if you can hear the reverb clearly on the small speaker it means there is too much of it usually. It will reveal if the bass is too loud too. You will learn what the correct amount of reverb and bass sounds like on the cube. It is interesting how much about the high end you can hear even when you cannot hear it well on the speaker. Excessive highs in your mix determine what you hear in the small speaker too.
 
There is a point when you can hear all the things in your mix nicely down low coming from a mono mix cube or small speaker and then when you monitor that up loud and in stereo again usually it sounds terrific and very well balanced. I find a small speaker mix can be cranked right up to 105 dB SPL plus (on the mains of course!!!) and the mix sounds fabulous still and does not hurt in any way. The spectrum appears well balanced. Nice amount of energy right from deep 40 Hz notes right up to 15Khz and beyond.
 
I am mixing a hip hop tune for a client and while the verses are sparser and clearer when the choruses come in there are a lot more parts and a lot of drama is added at this point. I have been having issues balancing everything on these loud choruses. I kept the music up on the mains thinking I would need to in order to hear all the detail better at these complex points in the music. In the end I pulled everything down to zero at that point and rebuilt the mix on the small speaker of the loud complex sections. I was able to bring everything back in again in the right proportions etc.. Then up loud on the mains it just sounded killer at these points now. It solved a problem for me.
 
I call it a small bottleneck to put your entire mix through yet when you do, it seems to create an almost microscopic view of your mix from another angle. It lets you hear when things are out of balance. Listen to quality reference mixes on the speaker to get an idea of how they sound too. Nice usually.

doncolga
Yikes...after listening on these the JBL's feel completely void of mids...I guess it's not so much they don't have mids as the Cubes don't have the extended highs and lows.

I bought a pair of the powered version of these as soon as they came out.  They will realy help with the kick and bass levels too.  If you concentrated on the low low frequencies for your JBL's, you might find the kick and bass void in the Avatone mix.  It lets you hear the low mid and high mid's much better.  Also if something is really edgey sounding on the Avatone's, you'll know your way over the top on the edge (I.e. vocals and guitars).
 
Kevin

One other thing, balance both monitor to the same SPL\db level so you can do an accurate comparison.  77db to 82db works well in smaller project studios, 85db in larger rooms.  Any difference in volume between the Avatones and the JBL's will give you a false impression due to the volume change.
 
Kevin