Twl pretty much covered most of what we need to know. I would just like to add a couple of points. First off, as we know, volume controls are really attenuators. When you connect a cd player directly to a power amp you are getting the full output and you need a way of taming it via an attenuator. You can use either the cd players' output control or gain controls on the amp.
As TWL mentioned, many cd output controls are in the digital domain. And yes, you will lose bits (resolution) as you attenuate. In theory you lose 1 bit for each 6db of attenuation. That's how we get 96db s/n ratio for a 16 bit device. Divide 16 into 96 and you will see what I mean. 24 bit devices (in theory) get you 144db of resolution.
As an aside, 24 bit devices are usually more like 20 bit because of various limitations like thermal noise, etc.
Personally, I prefer to use an active preamp, staying away from external volume controls and passive preamps.
Jim
As TWL mentioned, many cd output controls are in the digital domain. And yes, you will lose bits (resolution) as you attenuate. In theory you lose 1 bit for each 6db of attenuation. That's how we get 96db s/n ratio for a 16 bit device. Divide 16 into 96 and you will see what I mean. 24 bit devices (in theory) get you 144db of resolution.
As an aside, 24 bit devices are usually more like 20 bit because of various limitations like thermal noise, etc.
Personally, I prefer to use an active preamp, staying away from external volume controls and passive preamps.
Jim