I am using Wadia 861 ( since 2004 ).
fisrt, I used a Sine-Wave reformer (regenerator/regulator) of small power handling (only 1000
watt) solely porviding power to the Wadia, it has been
very good. Then I have purchased 1 x RGPC 600s
and found slightly different result if the Wave_reformer
is plugged onto the RGPC than using the RGPC plugged onto
the sine-Wave reformer, the latter is a little better
may be becuase the source power from wall socket is already
from dedicated line, not too bad a power source,
the merit of the RGPC is more when it is just before the CD, but in this way, no other gear can use the RGPC.
If it was just for your question, my suggestion is that
( if no other "enhancement" considered together, or only deciding the first addition to the system, the wave-reformer imporving the source CD./DAC is a good choice & important,
"always work from the source first "
then the next stage later is to upgrade the power for
the pre-amp........
If you wish to improve simultaneously pre-amps & CD
try Synergistic Research Power Cell, I had one from a
dealer/friend just last month, it is 3 x RGPC's cost
I cannot tell if any combination ( making up same money
value ) to out-perform or not, as cannot have them
all together at home. But stand alone , it beats
1 x RGPC .