04-12-12: GooddominoSensitivity (the input voltage that will result in the amp putting out its maximum output power) is not directly relevant. What is relevant is the gain of the amp (the relation between output voltage and input voltage).
My Krell amp has an input sensitivity of 1.34 V RMS and gain of 26db. Looks like I need an amp with lower input sensitivity . Not sure how the gain number factors in.
Comparing sensitivity numbers is only meaningful if put in the context of the power capability of the amp. For example if two amps both have an input sensitivity of 1 volt, but one of them is rated at 50 watts and the other at 500 watts, the 500 watt amp will produce much more volume in response to a given input signal than the 50 watt amp will produce.
The suggestion George made earlier about trying a pair of Rothwell attenuators seems to me to be well worth trying.
They would be connected directly to the input jacks of the amp, with no intervening cable. In conjunction with the 47K input impedance of your amp, the 10 db version would result in the LSA seeing a load impedance of about 30K, which is on the low side but I suspect would still be ok, given that it won't vary significantly with frequency and given the 620 ohm output impedance of your source. I am not familiar with the characteristics of the 20 db version, but I would guess that it would present a load impedance that is significantly higher (and therefore even better).
Regards,
-- Al