I have been looking at DIs, and notice that a lot of very popular ones, such as the Radial JDI, have a very low imput impendance. A lot of passive ones have input impedances in the 10k range and actives have impedances in the 100k range. Shouldn't these low impedances be affecting tone? Especially with a passive bass or guitar? Do people put a buffer (or a buffered effect) in front of the DI? For an active DI, it would be trivial to put a fet or opamp based buffer in front that would have 1M to 10M input impedance. Why don't they?