This might sound like a stupid and unimportant question, but i was thinking of it last night...

i have a volume control on both my cd player & headphones, in order to obtain the best sound should i regulate the volume via the control on the headphones or on the volume control of the cd ?

i.e, full blast on the knob of the cd and regulate the volume via the headphones or the other way around ?

If you don't ask you'll never know!

A guess: both controls are plain variable resistors in the signal's path, therefore there is no technical difference. You would want to use the "higher quality" control, but probably the quality is about the same. Another guess is that two resistors are worse than one, so you want to keep one open (maxed out).

So, go for convenience - cd maxed, control with phones.