Gain Matching - need advice


I recently added an Audio Research Ref 6 to my system (it was a dealer demo unit so price was right).  The preamp is paired with Pass Labs XA 60.8 amps (26db gain and 100K ohm input impedance) and Avantgarde speakers (sensitivity of 108 db at nominal 8 ohms).  The problem I am having, that I did not have with my previous Joule Electra LA150, is volume control.  The AR preamp has a 103 position volume control.  At position #7 the volume is almost ear splitting.  Sure I can turn it down but it’s very difficult to dial in a suitable volume.  I am inclined to blame it on the new AR preamp (output impedance of 600 ohms and 12db of gain).  I am stuck into using balanced interconnects which I won’t go into.  My first conclusion was that I have a gain matching problem since the old preamp did not behave this way.  Looking at the difference between the output impedance of the preamp and input impedance of the preamp ... why would there be a gain matching problem (at least as I understand the subject ... which I may not.  Anything that can be done about this, or a new preamp the only solution?
chilli42
This Schiit SYS will do the trick. You can put it in-between the preamp and amp, or in-between the source and your preamp!
https://www.schiit.com/products/sys
The attenuators mentioned by others here such as the Schiit won't work for you - they're unbalanced and you're using your Ref 6 in balanced mode. Talk to your dealer - he can install resistors on the Ref 6 input.
Parts express has balanced attenuators, but if the dealer can install resistors to attenuate I think that would be a better solution.