Much kudos to @alandbush , who exactly predicted the error I made yesterday. Oddly enough, I recalled reading @LupusAlpha 's instructions "Select 'Measure' and make sure you have the same parameters (sweep length, aso) you selected for generating the sweep." Relaxed over dinner last night, my subconscious brain recalled that I had fiddled with the measurement frequency range, that must be it I thought. Later I read the post above and felt a bit of an idiot. Oh well.... Anyway, I tried again this morning and I have some results, and very interesting results they are too.
Having fixed yesterday's issue, I tried to generate a curve using the SOtM kit, this worked fine. To get a quick comparison, I ran the system again using Roon AIR. This showed very little divergence from the SOtM curve. I then went through all the hassle of re-installing the mR into the rig, retried the test, and again, not much in it. In the bass region the curvers show virtually zero difference, the screen shot below is mid-range up, this does show some divergence but considering the absolute accuracy of the test, I would say there is nothing in it. Note the colours, Roon AIR red, mR green, SOtM blue. In the very highest frequencies, say 6kHz and upwards, the green and blue lines (mR and SOtM) run virtually on top of each other, even if you zoom in.
So in other words, maybe I think the SOtM kit sounds brighter, but it does not measure brighter. This is perhaps no surprise and backs up the 'bits are bits' argument, but of course it does not answer the question as to why the HF of the SOtM kit irritates me in a way that Roon AIR and the mR does not. What it does do is eliminate the thought that the SOtM kit is somehow intrinsically brighter and indicate the issue is elsewhere. I have a few ideas as to what the issue might be, I will report back if I find anything. Meanwhile, there is no need for anyone to mention SMPS's, the Gui test is planned.....
I have to say I am quite pleased with the above result. @thumb5 posted about how objective measurements can help with the troublesome psychology of subjective listening, we will see how this one works out!
Irrespective of this, the result has given me clarity as to what to do next. After this diversion, it is now back to the original plan, "operation listen to lots of music." 
Having fixed yesterday's issue, I tried to generate a curve using the SOtM kit, this worked fine. To get a quick comparison, I ran the system again using Roon AIR. This showed very little divergence from the SOtM curve. I then went through all the hassle of re-installing the mR into the rig, retried the test, and again, not much in it. In the bass region the curvers show virtually zero difference, the screen shot below is mid-range up, this does show some divergence but considering the absolute accuracy of the test, I would say there is nothing in it. Note the colours, Roon AIR red, mR green, SOtM blue. In the very highest frequencies, say 6kHz and upwards, the green and blue lines (mR and SOtM) run virtually on top of each other, even if you zoom in.
So in other words, maybe I think the SOtM kit sounds brighter, but it does not measure brighter. This is perhaps no surprise and backs up the 'bits are bits' argument, but of course it does not answer the question as to why the HF of the SOtM kit irritates me in a way that Roon AIR and the mR does not. What it does do is eliminate the thought that the SOtM kit is somehow intrinsically brighter and indicate the issue is elsewhere. I have a few ideas as to what the issue might be, I will report back if I find anything. Meanwhile, there is no need for anyone to mention SMPS's, the Gui test is planned.....
I have to say I am quite pleased with the above result. @thumb5 posted about how objective measurements can help with the troublesome psychology of subjective listening, we will see how this one works out!
Irrespective of this, the result has given me clarity as to what to do next. After this diversion, it is now back to the original plan, "operation listen to lots of music."
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12
