Mounting any tonearm at a non-designed distance from the spindle necessarily alters the alignment geometry. It will be impossible for the stylus to track the arc across the platter that was intended by the tonearm's designer.
If an arm must be mounted farther from the spindle then the cartridge is normally moved outward in the slots by a similar amount. This allows zenith to be aligned at the points the arm was originally designed for (Baerwald for a TriPlanar), albeit with a flatter tracking arc. This in turn necessitates skewing the cartridge slightly in the headshell.
Whether the tiny reduction in tracking angle error from the flatter arc would compensate for upsetting the arm's intended force vectors from a skewed cartridge is impossible to predict with certainty. Personally, having heard both misaligned cartridges and rigs played with and without rings, I wouldn't bet on it and would want to compare.
BTW, whether it would even be possible to attain the TriPlanar's intended Baerwald alignment in your friend's setup will depend on the stylus-to-mounting screws dimension of his cartridge. Some cartridges wouldn't be long enough to attain alignment with the arm moved that far back.
I hope the designer knew which cartridge your friend was using and that it was in fact long enough to be aligned with the arm mis-mounted by 2mm. If not, his advice was in effect a statement that, "My ring is more important than aligning your cartridge properly". Unless he's tried it himself with the same cartridge and tonearm, he couldn't know that and his advise would be merely self-serving.
Even if he did know the cartridge could be aligned, I hope he advised your friend to compare the sound with (a) the arm and cartridge mounted normally, without the ring, and (b) the arm and cartridge mounted abnormally, with the ring. These setups would certainly sound different but I doubt anyone could predict which would be "better".
When forced to choose between compromises, the user should listen and decide for himself (or resolve the problem with radical methods, like our brave friend Kostas).
If an arm must be mounted farther from the spindle then the cartridge is normally moved outward in the slots by a similar amount. This allows zenith to be aligned at the points the arm was originally designed for (Baerwald for a TriPlanar), albeit with a flatter tracking arc. This in turn necessitates skewing the cartridge slightly in the headshell.
Whether the tiny reduction in tracking angle error from the flatter arc would compensate for upsetting the arm's intended force vectors from a skewed cartridge is impossible to predict with certainty. Personally, having heard both misaligned cartridges and rigs played with and without rings, I wouldn't bet on it and would want to compare.
BTW, whether it would even be possible to attain the TriPlanar's intended Baerwald alignment in your friend's setup will depend on the stylus-to-mounting screws dimension of his cartridge. Some cartridges wouldn't be long enough to attain alignment with the arm moved that far back.
I hope the designer knew which cartridge your friend was using and that it was in fact long enough to be aligned with the arm mis-mounted by 2mm. If not, his advice was in effect a statement that, "My ring is more important than aligning your cartridge properly". Unless he's tried it himself with the same cartridge and tonearm, he couldn't know that and his advise would be merely self-serving.
Even if he did know the cartridge could be aligned, I hope he advised your friend to compare the sound with (a) the arm and cartridge mounted normally, without the ring, and (b) the arm and cartridge mounted abnormally, with the ring. These setups would certainly sound different but I doubt anyone could predict which would be "better".
When forced to choose between compromises, the user should listen and decide for himself (or resolve the problem with radical methods, like our brave friend Kostas).