Ok more news,
From my listening trials,
This "new" cap to upgrade is more important in quality over size,
Which Redge78 is currently finalizing..
So we are talking about, and very similar to coupling cap quality...
What I can also say,
For those that have an MK8, the clarity increase actually allows you to easily differentiate between the power tubes..
In case no one realizes, there IS NO tube swap available for MK8 power tubes,
Except for only three made types,
In which only the DR supertube was said to be best....
I have two, the EH gold pin, and the elusive Russian "DR" Supertubes...
Now with the mod in place,
there is NO LONGER any clear superiority of the DR tubes...
Instead a more clear differentiation of their positive traits...
They are more like just a tube swap, with preference being the
choice, not superiority..
So it is now clear that the DR superiority was its ability to perform superior, under "non" optimal conditions...
Now that this new cap upgrade is in place, the performance of the powertube circuity is elevated to let the tubes perform more optimally, removing the DR's advantage....
Edit: this observation is specific to parameters of this amp's circuit.
The MK6, having a larger tube with 8pins, does have different WCF grid resistor locations,
that may or may not need upgrading(depends if you have blue resistors)...
But the cap upgrade is the same.
You WILL hear
BOTH :
a more holographic clear performance
and a more tube characteristic performance
Edit:
Also, as mentioned in beginning,
the cap upgrade itself will also introduce its sonic trait/influence on the performance as well,
So my suggestion of sound quality over size is in order.