help........

P.S: I neglected to mention that the approximately 30K input impedance I cited for the Rothwell attenuator applies to its 10 db version (and is based on measurements I have performed). But I suspect that the corresponding figure for the 15 db and 20 db versions is even higher.

Also, btw, the input impedance I cited for the Harrison Labs attenuator is based on measurements another member reported here a few years ago.

Regards,
-- Al

I originally purchased the SYS as I thought I needed it between the preamp and amp to be able to turn up the preamp volume control a higher amount.  I then realized that my system was OK without it, i.e. that the volume control on my preamp could be turned up high enough without it.

I then happened to purchase a pair of monoblocks, and am using the tiny SYS as an enjoyable passive mini preamp, for two different sources. So for $49 + about $5 shipping you have a multiuse little gizmo.

As an alternative to the Harrison Labs attenuator the OP may want to consider Rothwell attenuators

+1  I have a couple of different values. I use them as needed.

@almarg 
Al - the max volume function limits the output volume - which means the preamp has to be turn up to achieve the same volume at the speakers.
You can also use the variable volume on the 203 to overcome the problem - the advantage of using the max volume functionality is that it prevents some idiot from winding the preamp up full volume and then pressing play - turning the speakers inside out.
If I recall correctly you can also set the volume on the 203 and then turn off the variable volume which means you cant increase the volume without going back into set up and turning the variable function back on.
 
In my view it is suboptimal to add another device and interconnects as is being suggested when it is not necessary to fix the problem .

@dover Thanks! So you've identified two approaches that can be implemented easily and at no cost. I suppose that what the OP will need to verify is that turning down the max volume or variable volume setting far enough to allow satisfactory range on the preamp's volume control does not degrade the sound. For example, as a result of what is referred to as "bit stripping." Whether or not that occurs will depend on the specific design of the Oppo, and probably also on how much either of those settings needs to be reduced.

And if perchance that is a problem, he's been given a number of other low cost alternatives he can choose.

Best regards,
-- Al