I agree with Timo. But as a Rowland Synergy IIi owner, I can tell you that, if you do audition that preamp, there are two secrets about it you need to know: (1) If you do a comparison with other preamps, boost the gain on all of the Synergy's inputs and compensate by lowering the output level with the master volume control. This improves the dynamics significantly. (2) If you buy the IIi, substitute an FIM powerlink DC cable for the stock Cardas cable between the preamp and power supply. For $600-$700 this makes another dramatic improvement in dynamics and some improvement in soundstage as well. Even with the FIM cable, the Synergy IIi is still a bargain, compared to the alternatives listed.
My small contribution to the 300's
Best Pre's over different price classes
Mark Levinson #32....the absolute best combo I have heard
CJ PFR...good combo for lesser speakers
YBA 3-2-1-Passion....very symbiotic combo
Be aware of the 1.3 volt input sensitivity and low impedance.
BTW the single ended inputs on your 300 are about 5dB quieter than the balanced,
Rowland is Ok, Klyne have not heard, 380 bites it, Threshold not a good idea either.
It would help more to know what speakers and Cd Player you own and notable listening room conditions and musical tastes.