Originally Posted by arnyk
As has been already mentioned, the ear's sensitivity to noise depends on both its amplitude as indicated by SNR, and also spectral content which is suggested by the weighting technique used to measure the SNR.
The easiest way to obtain an amplifier with low absolute noise output is to get the power as low as you can.
Pass labs specifies output noise in microvolts which ignores the spectrum part of the equation:
BTW they spec the same noise output regardless of power from 30 watts to 200 watts, which seems strange to me. 200 uV is not IME an exceptional number. 200 uV is about 80 dB below 1 watt which while not exceptional is probably good enough unless you stick your head inside the speaker cone in a very quiet room.
another point to mention, with preamp disconnected, there is zero hiss from the amp. Clearly my marantz 8801 is a limiting factor and adjusting the volune knob or no source input doesnt help the hiss. The outputs on the preamp are simply noisy.
I'm not sure if upgrading to "ultra high end" like theta digital or datasat would change this problem with high sensitivity speakers. Avantgarde Acoustics makes a pre-amp that is stereo only that works with high efficiency speakers that apparently solves this problem but that is not a good option for my home theater. Theta casablanca also lacks the number if channels i need for home theater. This would literally leave the $20000 datasat as the only contender ... But processors depreciate SO badly that the money is kinda down the toilet once you pony up.
Parasound makes a pre-amp that is stereo (jc2) with home theater bypass inputs for the main channels of your home theater but I am not sure how good it is about hiss, etc.
None of the manufacturers seem to test their gear with high sensitivity speakers.
You would think I was insane and obsessing about this subject and that maybe I should change my speakers... If you heard the avantgarde speakers though you would change your mind... The typical layperson can tell they sound like the "voice of god" and they are clearly the best part of my chain of equipment. These speakers make sound that literally is BLISS... A sound so addicting for almost any type of music that you cant leave the chair. My room is already Very well treated and my overall room response is already beautifully linear.
These silly hiss problems seem to be solved by a -20db xlr pad in-line with the preamp and amp BUT i am not sure this is not in some way affecting the overall signal purity. I think xLr pads maintain the impedance while simply making you turn the preamp vomume up higher to reach desired volume. In the preamp i have the main speakers set to +8db (which is what audyssey did ... In addition to adjusting all other speakers to match). This cut the hiss at idle to near inaudible at sitting position... But is there a "better" way acoustically or is this as good as it gets? I suspect that maybe the avantgarde made preamps made for high sensitivity speakers do exactly what I did: cut the pre-amp's gain at idle by having an in-line resistor network... And then charging the end user $10000 extra... LOL. Maybe i am being cynical.