Do Plinius amps have high frequency anomalies?

I perceive the area of principal coloration to be in the sibilance range and it seems to add a slightly whistle-like character to the sound, especially at high levels. On some (maybe rolled-off) recordings, this emphasis can be attractive, enlivening the string and brass sheen that occur naturally; but on most cd's and lp's, the effect is not to my taste.

I experienced something similar to this during my recent audition with the latest Plinius Hiato integrated amplifier. My product audition experience HERE goes into more details.

I own the SA-100MkIII. Instead of experiencing sibilance and a slight tilt in the high frequencies, I got a smooth tube-like midrange with a treble that's just right. It depends on the speakers you are driving with the Plinius. The Plinius has a dark character and with the equally warm Sonus Faber Grand Piano speakers, the sound can get pretty dead as both treble and midrange were kind of shut-in causing music to lack sparkle and dynamics. With more neutral speakers like the PMCs, the sound opened up a little albeit still a little to the warmer side of things. With brighter speakers like the Proac Tablette 50 Sigs, the matching was better. In all cases, I did not find the SA-100MkIII to exhibit high frequency anomalies with most range of speakers even the brighter ones. Not too sure if the Shahinian Hawks are very bright speakers. You can try a warm tube preamp or warm cables to ameliorate the high frequency anomalies. Another possibility is the acoustics of your room. If your speakers are close to bare walls, chances are the anomalies, especially high frequencies are caused by the room acoustics due to reflection of sound waves off the walls. Some absorption will solve this problem.

FWIW I used dynamic interconnects to boost the mid to high frequencies on the Plinius amp. I have 2 sets of XLO Signature 2 cables throughout from CDP to preamp to the SA-100MkIII, and my preamp is lean-sounding.

Might be an impedance issue.

Yes what you have described is true, it lacks finesse in the HF response. there is a resolution in the making as we speak.

Out of curiosity, have you tried other amps in your system and not found this issue? Guess I'm just wondering how you've determined this is due to the amps and not possibly the preamp, speakers, source, etc.?