hello, anyone knows what is the icbm signal to noise ratio output?

for example i have heared a dinstinct loss of signal after wiring my icbm, the level of the sound coming out from my speakers being less that what it was before, at a same preamp level

today i want to use a tube amp to drive my main speakers but this amp is only 2*20W
having 92db/W speakers i can just manage with a little loss until it gets bad

so anyone knows what is the signal to noise ratio of the ICBM?

thanks
fred