I hope this will help people in similar situations, i.e. hiss from the DSD Snr dac due to high gain amps and high efficiency speakers.
I found a great solution, at least in my system : the Placette RVC between preamp and amp(s) is completely transparent and solves the hiss issue.
It is also great as a replacement for the preamp, although I slightly preferred my Plinius Tautoro (which costs a lot more).
Guy Hammel at Placette is a pleasure to work with, and his cables are excellent, competitive even with Wireworld platinum.
No wonder this device got a Stereophile class A rating.
Placette Audio offers a 30 day free trial, like PS Audio.
I have no affiliation with Placette, I just want to help people with a hiss issue.
The Placette RVC is not cheap, at 1295 USD plus shipping, but in my system, it’s the only device that solved the hiss issue without negative SQ impact.
On the contrary, I am getting better sound, probably because I can now use the full range of volume of my preamp, and the hiss is not masking low level details.
I tried cheap inline Rothwell attenuators before the monoblocs but in my system, that killed the sound.
I also tried a Townshend Allegri +, which was very good too, but I slightly preferred the Placette.
In my system it is more transparent than the DS attenuator.