After a lot of tweaking, I was finally able to get my Sansui AU-517 to work well with my Omegas.
Previously the amp was overpowering, and could only be used at 5% volume before getting too loud. There is a switch on the back which internally de-couples the power amp from the pre amp for use independently. I used a pair of -12dB in line attenuators and a short RCA cable to externally reconnect the two stages and lower the input voltage into the power amp section. This has allowed me get much more play out of the volume knob. Its got some other nice features which I find useful such as tone controls and two phono inputs.
I plan to use this combination for a few weeks before comparing against my 2 wpc SET amp to see what changes I notice.