Volume control


When I use my CD player through my tube preamp I turn the volume control no more than 9 o'clock on the dial. However when I connect my Oppo to the preamp I need to turn the knob of the preamp considerable higher. I also need to turn the volume up on the Oppo. If I connect the Oppo directly to my amp and bypass the preamp, I can reduce the volume setting on the Oppo.
Any ideas as what is causing the volume difference?
Thanks
elf1
elf1
Which Oppo do you have? Does it have a "power on" setting for the variable volume? Perhaps your variable volume is set to a lower level (not full output).

Modern CD players have a max output of about 2 Vrms. Your Oppo probably also has a max output of about 2 Vrms. Theoretically they would be pretty close in volume. That is, unless your variable volume control on the Oppo is set a level less than max volume. Do you know if your Oppo has the volume setting pre-set at a certain level? If you set the variable volume on the Oppo to max, it should be relatively close to your CD player.

But! Be careful if you are connecting the Oppo directly to your power amp (bypassing the pre-amp). If you have the volume set to max output when you play a cd through the Oppo, and the volume is set to max, it is going to be VERY LOUD!
Thanks for the response. My preamp is Audio Research SP6 and my CD player is a Rotel. The amp is Bryston 4B st. I do not know the sensitivity of the amp. My Oppo is model 105. 

The output voltage of the AR SP6 is higher than the Oppo's. If the input sensitivity of the Bryston 4B ST is similar to the Bryston 4B's you should be able to achieve maximum power output with either unit preceding it before having the volume control at the maximum setting.

Remember the volume control acts more like a brake than an accelerator. In this case the lower output voltage will allow greater range and perhaps more consistently precise volume control settings.

Any ideas as what is causing the volume difference?
Hi @elf1

Regardless of what's causing the volume difference, in all likelihood you don't have any problem or issue with your gear. IMO, 9 is fine, despite what some proponents of 10 or 11 will claim. Also, keep in mind that irrespective of your CD player, OPPO, or other source, the "level" of the program music source itself also plays a major role, perhaps the most important role.