In your application, the loading resistor is acting as a voltage divider which, given its high resistance, mean that only a small portion of the signal is going through the resistor and being burned off as heat. It is not a critical part whose quality will matter greatly. Is it still worthwhile to seek the best? Probably, because everything matters. What is then, is the best? That is harder to know because “best” is always a matter of specific application and personal taste. I know a number of builders who dislike the sound of quite expensive Vishay resistors, finding them to be “dry” and lacking in harmonic richness. I had a linestage, which I liked, that extensively used Vishays, so it is a matter of taste and application. The company that consistently produces very good components—Audio Note—makes some pricey Tantalum and Niobium resisters that I would bet sound good if you don’t mind spending something like $40 per resistor.
