Sibilance

On the other hand, if I recall correctly, yours is not the first mention of sibilance on Barbour LPs. So in this case, it might be the LP. Do you hear sibilance with other vocalists? I also doubt Patricia gets up to 3-4KHz ( per Mijo) in her vocal range.

I bought this record about six weeks ago, and changed amps since then. Listened to it again all the way through this Sunday. No sibilance with either Raven Osprey or Rogers EHF-200MK2.

I have this LP and zero nasties in a sibilance. Most likely a product of your setup. 

My benchmark for this is Cowboy Junkies Trinity Sessions.  I’ve tried both an AT Art 9XI and a Koetsu Rosewood and a wide range of VTA setting with little change. I found changing cartridge loading helped the most. 

I have the first Trinity Sessions vinyl I bought in the 1980s. It has issues.  The recording engineer re-released this record a few years ago and cleaned up a lot of the sibliance in the recordings. Some would argue art is not without its flaws but I enjoy the newer version more than the old one.