I agree completely with Fcrowder in that it depends upon the position in the circuit. Fcrowder, please correct me if I'm wrong, but I think your resistor comparison tests were utilizing series-configured resists on the volume controls so you were actually listening to the additive effects of several or many resistors in series. Though I completely agree with your findings as I performed a similar test with my DMC-10Z, I found that the noise contribution from a single Holco, Resista or Caddock as in a ladder-type volume control to be much more satisfying than in the series configuration. The Vishay "metal foil" is still the most transparent for low-level applications, but they simply aren't feasible in high voltage/power applications. The only problem with Holcos are that they don't like high voltages (>150 V) regardless of their specs, and you must be very careful when bending their leads. If the soft-metal caps on the ends of the ceramic tube are distorted, they will become noisey or fail outright. However, even with these cautions, they are still an excellent resistor.
Goodluck with your DIY projects,Dismal. They can be very rewarding.
Goodluck with your DIY projects,Dismal. They can be very rewarding.