Types of passives should at least be mentioned. There's a transformer type I know zilch about, and three resistive types: (1) potentiometers, (2) series stepped attenuators, and (3) ladder stepped attenuators. Almost everyone would agree that (3) is much superior to (2): I've built both with identical resistors and comparable rotary switches, and the difference is easily heard. Some very costly pots may be competitive with (3), but most are clearly not, IMHO. Whether passive or active is better is an unending dispute, but everyone would agree that it depends heavily on the system, in several ways, and that passives are trickier to deal with. In my opinion, they're well worth it, but others will disagree. It's a much-discussed topic in this Forum: maybe you could look up those discussions.