What is the Sound of Impedence Mismatch?

Thank you, gentlemen.

I am playing with a First Sound Presence Deluxe tubed line stage, which has an output impedence of 1700 ohms. It's very happy with my CJ 11a at 100K ohms input impedence. But with the Pass X-150 (spec sheet says 22K balanced, not sure what it is unbalanced, which is the way I am running it), the sound is, if anything, a bit bright and over-etched. No problems with bass or dynamics, definitely not lifeless, just tilted up a little. From your descriptions, it doesn't sound like this is a technical mismatch, however. Could be a listener mismatch :)

dan

Sounds like the Presence has too much "presence". Which tubes is it using? Sometimes a simple tube swap is all that's required to restore a more pleasant tonal balance...
Of course if you are just borrowing the piece and can't change the tubes, that's another matter.

No, I own the piece. To tell the truth, I don't know what tubes are in it. I'll have to open it up and check.

I've read that bass rolloff (happens due to interconnect capacitance) can be caused by such an impedance mismatch where the pre's output Z is too high for it's PA load, so you might have such an issue Drubin.
Have you experimented with different upgrade AC cords though?

No bass problems, actually, so that suggetsts no impedence mismatch. I need to experiment with cables and will also try power cords.

Wouldn't it be great to have a concise set of rules of thumb for system problems? Guidelines for identifying an impedence mistmatch, or cables with capacitance that is too high, too low, etc. Am I dreaming? It's just that it feels like most of the time I'm drifting around rudderless when some basic principles would help the navigation a bit.

While I'm at it, let me offer up my idea for the audiophile test CD I'd like to see. The Chesky Ultimate Demo disk is pretty good, but I'd like to see someone produce a disk that demonstrates the unwanted side of things. This is what grain sounds like. This is what midrange suckout sounds like. This is bad VTA ... azimuth mis-alignment. This is wooly bass. Clipping, even vs. odd-order harmonic distortion. You get the idea.... Even though the playback system would alter what you are hearing, I think you'd be able to get the picture if it is presented relative to a reference. Would be tremedously helpful to me in terms of calibrating my vocabulary with others.

-----Dan