Was reading this thread about a great looking and expensive preamp this morning, and it got me thinking. After having been through all kinds of gear periods and having lugged a bunch of different rigs around over the years, I started thinking about the things that I come back to as always being important in an amplification setup. The two big ones seem to be a high pass filter, and input impedance loading that is "friendly" to the pickup being used. Once you have those things, there are a lot of amps out there that can provide a pleasing enough color to amplify that initial signal. All of this lead me to reread This thread this morning and set me remembering our little get together fondly, but it also got me thinking about the topic of variable input impedance again. It seems to me that if I were designing the perfect preamp - or of putting together the perfect feature set in a portable rig that I could take with me when I travel - the Grace unit from the first link would have just about everything I could want except for sweepable input impedance (it has a sweepable HPF and tons of EQ control). The fdeck HPFpre has the sweepable high pass filter, but little else. The Summit TD-100, from what what I can remember, was a great sounding unit, but as Phil noted, it's "built like a pig". Even so, I find myself wishing I could try one with my current amps to see what kind of a difference it would make. Anyway, after all of this rambling, I come back to two thoughts, which I will phrase as questions: 1) How many commercially available units are there out there that have this variable input impedance knob? 2) How hard would it be to design a little box like the fdeck HPFpre that loads input impedance? It seems to me that if I could carry these two controls with me, I'd be in pretty good shape to find a sound on almost any amp.