Mo, if you mentioned it before, I missed it, but how did you find that the output impedance of your Denon is 10K? That seems rather unlikely since, as we discussed before, typical receiver output impedances are in the hundreds of ohms with few if any significantly over 1000 ohms. As I'd mentioned, for example, Onkyo specifically stated the spec as 470 ohms. I also saw a lab test of a Denon receiver from a few years ago in which the output impedance of the preout measured 1000 ohms. Again, if the number is actually in this range, your measurements and calculation would put the EP600 input impedance in the area of a few hundred ohms, which would be far lower than any I ever heard of.
Any preout number from a few hundred to a thousand ohms would work well with amplifier input impedances which are typically 10K ohms or more(usually more), therefore satisfying that 10/1 ratio rule-of-thumb for good performance(and receivers typically have sub outputs with plenty of voltage). I'm still waiting to hear what the input impedance of the EP600 amp actually is.
