The only thing that could stop this, is honest and open communication from Kemper. Tell us what have changed, how it affected the aliasing, and why is it that sure that the sonical qualities have not changed. Without these I can only depend on my findings. And those are that 1.5 is different (for me better).
This is what I wrote in an earlier post:
I checked intensively through studio monitors and headphones and I can say, that both tracks sound absolutely identical.
We had a number of producers and pro guitarists checking these tracks. Same result.
We have made a spectrum analysis of both tracks. No difference in the high end.
We have not changed the code in terms of sound. Only the aliasing issue and the Green Scream were addressed. There was no need to change the anti-aliasing filters.
For some of you this message was "disappointing", or not honest, as I learn.
I understand that you will not accept anything else from me than saying: Yes, we have changed the tone - sorry, we'll bring the old feeling back. Because so many people cannot fail, that would be only honest statement.
But I have to repeat myself: We didnt change the code in terms of tonal characteristics and feel. There was no need to.
In the mean time we had the chance to make a complete A/B comparison. We had a brand new Profiler Rack version with 1.60, and a white Profiler Head from December 2011 (first series) mixed and played through Genelec studio speakers. We used an A/B switch to feed the guitar to either the one or the other Profiler. That is the optimum setup for an A/B test of firmware versions.
We had to balance the volumes of both units in 0.1 dB steps first, because the ear can be fooled by the slightest energy difference.
We had seven people participating, each one with 10 to 30 years of experience as a musician and producer/mixer. Four of them were guitarists, two of them below 30 years old, with a possibly better hearing.
We played the guitar round-robin, to everybody could catch the feel of the sound, while the others listened to the sound itself.
Later we used a looper as a "reamping" unit for checking differences in the pure frequency responce by eliminating the human variance in playing. We played different rigs, from clean to high gain. We did blind tests too, since every participant was trapped by his own imagination, and everybody was aware of that.
We tested for more than two hours. The result: Both units sounded exactly the same. It was not even possible to work out a slight difference, that could be owed to the different hardwares from different series. I had expected an ever so slight difference, so we would have swapped the hardware to see how the difference would change. But nothing. Not even a difference in perception by the improved aliasing.
We did not make any recordings (exept the looper) or matchings, as we trusted the most accurate sound measuring device. In our case it was 14 well trained and experienced ears.
If there was a difference that big, that you would hear it after minutes of updating, or even the other day, it would have been revealed in the first seconds of this perfect A/B comparison, where there was no pause between switching between 1.54 and 1.60.
Conclusion: there is no evidence where we could correct the firmware. No clue what to change.
However, this will still not satisfy you, as you hear what you hear and so many users have heard it, and so many cannot fail.
By the way: there has not been a single firmware update last year, where at least two users posted about a possible sound change. Now we've got the critical mass. This thread will go on forever.