No harm in trying
either the 0.775V or 1.4V RMS with the Crown amplifier. When using the 0.775V selection the Master volume on the marantz will
increase sooner than the 1.4V selection. But also it depends what input source U use more frequently and @ what SPL level do U play the system for normal listening levels. For example, the 7005 has a phono input (mm) and often when using a lower output phono cartridge one must turn the Master volume level
significantly higher to reach the desired listening volume level. When this happens and the Master volume level is set quite high then negative byproducts could be audible such as preamp's noise floor.
The basic CE industry dilemma has do when U are mixing a consumer product (Marantz) with a pro-audio component (Crown), as in the consumer field typical Japanese products have low pre-out levels whereas in the pro-audio product higher pre-amp levels are more common. Thats why Crown has provided both...
Though the PSB loudspeakers are rated 6 Ohms nominal, most of the test reviews indicate they are more like 4 Ohms. Running the Crown amplifier with the 0.775V selection simply provides a higher input swing of the pre-out to the Crown. No harm in trying either...
I would suggest that U set the Crown gain controls @ about 70% rotation and then double check for volume level to make sure the Crown amplifier is not clipping. Also if U have the Crown Series 2 2002 U can monitor the front panel clipping levels by its LEDs...
Just my $0.02...