Volume control vs. attenuation control

It's highly advantageous to play around with both controls in order to match amp and pre. I would consider myself lucky to have such ability. You want enough gain in each to optimize sound quality and not too much as to cause distortion. And you want pre to have enough in relationship to amp's sensitivity but not so much as to overdrive the amp causing undue distortion. Hopefully other members will give a more technical explanation, but optimum settings will be dependent on speakers (and source). Will be dependent on how demanding are the speakers.

Technically an 'attenuator' cuts the signal before any amplification stages.
Like my VAC Standard preamp, the 'volume control' really attenuates the incoming signal ONLY. so the preamp is always set to amplify that signal (from the input attenuator 100%) Thus it uses an "attenuator' and not really a volume control.
A volume control actually changes the active amplification of the signal, from well below less than what it comes in as, to increasing it. (many preamps sound better in the latter form, rather than cutting the signal.
A few preamps have two volume controls. And attenuator, AND a volume control.
(Like my Audio Research Sp-15) so the attenuator is set in large steps, 6dB each, and the main volume control has the usual many gradations. So the setting of the attenuator can be set to allow the best use of the main volume control. (which sounds best if in the top third of the control rotation generally) I like the design a lot. Only a device to set each input would be more useful.
but basically it only matters how it sounds to you best.

All volume controls are attenuators. Gain stages amplify the electrical signal and attenuators, either before or after a gain stage, reduce the level of the signal.

The setup up Markpao describes will allow him to play with both attenuators to achieve the combination of lowest signal to noise ratio and flexible volume control settings.

In your case you're describing gain control vs. attenuation control on your preamp section that should be set to the best possible volume range that you want to operate your volume control for ex 7...12 o'clock. If you feel that you get distortions on the most of your listening range try to adjust one way or the other untill you get the most of sound and leave the gain control untouched.

I would try the combination you like, then do some critical listening. A/B between that and their suggested setting, and see if you loose/gain anything. If it sounds the same (better possibly?), go for it.