A couple of comments...
First there are a lot of cartridges that are excellent but sound different...
Asking for something objectively better than a V15IV-SAS is a very tall ask..
Consider:
1) The core poles of the V15IV use sophisticated lamination to reduce non linearities that are common to both MM and MC designs. (some MC's do similar things with other methods, eg: the Lyra designs, and Denons from the DL304 up)
2) The SAS stylus uses a cantilever made of solid boron with an ultra light magnet - so great rigidity, and very low effective mass - it should be lighter than most MC's, and in fact on a par with the very best.
3) The SAS needle is the Namiki patented microridge / microline type - regarded as one of the top 2 or 3 stylus shapes. (there are debates about which sound better - but this is certainly up there competing with the very best)
In terms of arm matching the V15IVSAS is slightly too high compliance for your arm, which is why the Shure design includes the damping brush - which works very well, and makes it a very good match for your arm.
So speaking objectively - by all objective measures - you would have a hard time doing better.
A different question would be whether you can optimise your system better to get the best possible performance from the V15IVSAS.
This implies looking at the turntable and arm setup and its tweaks (isolation, etc..) - then at the phono stage quality - and whether the loading is adjustable....
Many (most) cartridges can perform better when their loading (capacitive and resistive) is adjusted.
The original manufacturers recommendations should be treated as a starting point guideline...
Personally I use a JLTI phono, which supports the use of RCA loading plugs to adjust the loading. (I had it modified to have an internal load of 500k, allowing me to vary the cartridge load from 10ohm to 500k...)
I run low capacitance cable from TT to phono stage - the phono stage sits right behind the TT - allowing me to keep the cable VERY short - the end result is total C of 60pf.
I can then increase the capacitance by either adding capacitive loading plugs, or extending the cable.
The SAS stylus does not have identical response to the OEM stylus - and may requires some loading adjustment to achieve an optimal setup.
I have SAS N97 and V15V but not V15IV, so could not comment on specifics for your setup - but I can definitely say that if aiming for the original OEM shure sound profile, you need to adjust the loading on the cartridge away from the default due to the difference between the SAS and OEM styli.
hope this helps
bye for now
David
