Sibilance -- that last little bit...

I took these same LP's to a friends with an HRX, JMW12.5 and Benz LP, Asthetix pre.....same noise. Yep the records sound great until INNER GROOVE DISTORTION hits!
Remedy....compact disc!

Begging to differ. The remedy is a better groove tracer than a Benz LP.

Focusedfx,
I'm unfamiliar with the 10x4 so can't say whether it can trace really tough inner grooves cleanly or not. I know a ZYX Airy 2 and above can, and that Benz's, Denons, Grados and Shelters cannot. They don't have the stylus profile for it.

I'm also unfamiliar with the WT protractor but I own the HFN record and its paper protractor. It's pretty poor stuff. If your arm is compatible with Baerwald alignment you should consider springing for a Wally Tractor or trying the poor man's version, the TurntableBasics. Either one should be superior to any paper protractor. The mirrored surface makes sighting and squaring the cantilever and squaring the azimuth of the stylus easier and more accurate.

An alternate consideration may be, that if the records evince this distortion on other rigs, perhaps the inner grooves have been damaged by previous playings.

True enough, though IME inner groove mistracing and physical groove damage sound very different.

I see where you are coming from Doug, but he describes the problem as "sibilance". Do you think that would indicate mistracking or groove damage?

Focusedfx, Does this sibilance seem to be equally strong through both channels? If it appears more in one channel, I would attack the anti-skate issue. I had a WT Classic 'arm for a couple of years and found it to be difficult to work with for anti-skate. I ended up with too much anti-skate because the other parameters were right in that setting.

The lack of a precisely determined pivot point, a suspended, partially floating paddle in damping fluid probably all contribute to small changes in geometry during play. It's a tricky 'arm, although a very satisfying one when married to the right cartridge, etc.

Could cartridge compliance vs. effective 'arm mass play a greater role in the inner grooves because of the viscous fluid being "moved" more by the rotation of the 'arm? Maybe a better cartridge compliance/effective mass match would help. Last I spoke to WT, they really liked the Sumiko cart's.

(I used the Dynavector 10X4 and Benz Glider with the WT Classic with good results. No inner groove sibilance. But...that was some time ago.)