Just checking in to say they are still breaking in. As shortly as two days ago I was not as pleased as i wanted to be.. So I decided to give them another week to ten days to really allow for full break in.
Partially due to using three.. so each gets less current.. So maybe taking longer to break in...??
Just a heads up I have not abandoned the project..

Another week, much better breaking in. Changed some
 

After 200 hours, the PATH Audio resistors seem more fully broken in. And sound better than previously.
With that, I decided to do a combo setup of one 3.9 ohm Duelund CAST with two PATH Audio 3.9 ohm resistors, and use the PATH audio 39 ohm 'trim' resistor (I would have also switched to try a 50 ohm trim, but then that would not be broken in... SO I am going to wait a week for that adjustment and experience)
Since all the resistors I did the merge with are broken in.. I feel confident the sound is as it will be.
The great part of the Duelund CAST were the glorious quality of the highs. and detail. The downside a slight tilt to the treble, with stronger upper mids and treble than midrange. Slight, but noticeable.
The PATH Audio resistors, after break in, pretty good balance. but not the glorious sense in the treble.
SO I was hoping for both ! combining the two types.

The sound is good. clear, precise. immediate. great hard edges, no slop. Good detail in the edges and HF.

I wonder it using one Duelund CAST and one PATH Audio could also have the positive results? But I am not willing to play with that at the moment.
(though I have some 2.5 ohm PATH and 2.7ohm Duelund which would also be 1.3 ohms, adding some trim and right in the ballpark.)

I think I have arrived at the final destination.
The only thing for myself to still experiment is to try a 100 ohm trim, upping the resistance from 1.258 to 1.283 ohms. And see what the combo I am using sounds like with no trim (1.3 ohms)


And just in time.. I am getting a pile of Butcher Block Acoustics Slabs arriving in the next few days. All Walnut. to see if I like them under equipment. Some roller block stuff is also coming, but not as soon.
I know I have not heard much from different underpinnings in the past. I am hoping the upgrades over the past year will change that.

Very cool, thanks for sharing.

Just a quick update. Tried the full 1.3 ohms with one Duelund CAST 3.9 ohm and two 3.9 ohm Path Audio. These all broken in.
Well the sound is fine playing Jazz and Classical. but for some Rock. I find 'too much bass'. (Which really just means for my apartment, there is more bass than I want, since I do not want to bother the neighbors in any way.
For any normal person, the 1.3 ohm total would be just fine.)
So I think I need to go back down a little. Adding next the 100 ohm Path trim resistor. (Which is NOT broken in)..
So that is going to wait awhile. since breaking in may take weeks.
In the meantime I am playing with butcher block and the (seriously disliked by some folks for 'killing' the sound) sorbothane "Isolate It!" stuff.
No room for a butcher block under my Marantz SA-10. so I used some appropriate for weight sorbothane pucks under the SA-10.
Yes better sound. tiny, but yeah. Also seems more midbass showing up. Tradeoff too. more liquid. but a little less in my face. So more laid back. also tiny change.
SO I have a pile of Butcher Block Acoustics chunks of wood to work with. I am just waiting on more sorbothane pucks and domes to work out how I want to arrange them all I have coming sorbothane sizes for 2-5 total, 8-16 pounds total, 16-32, 28-68, 52-132 pound for four feet. Should cover any combo I can need for butcher block and amp, or other things.
I gave up on rollers. as my first attempt was worse than better. Still have one under a CD changer... no real difference. The hassle seems more annoying than the positive results.
After I settle the footer butcher block thing, Then I will go back to the trim on the 20.7 midrange.

Wanted to update.. been a couple of months, and can say the 1.3 ohm resistor setup is a keeper. No anomalies, all is good. Sound is balanced and fine. My fiddling with various exotic wood bits under near everything is my new obsession.
Success declared, experiments completed on the Magnepan 20.7 midrange resistors