Your question is very similar to the other question you posted in the HT forum regarduing the B&W 685's. At that time I recommended 70 to 100 wpc of high current power for these speakers and still do.
Look at it this way. Watts are very cheap now compared to what they were in the seventies. Most speakers back then were highly efficent, 8 Ohm designs and could thrive on the 30-40 watt receivers that were common back then. Not today. Watts per channel have come way down and most speakers are designed at lower impedences to suck up this power. The 685 has a sensitivity of only 88 db and while it is a nominal 8 Ohm speaker, it has impedence dips of 3.7 Ohms. This means it will thrive and performs its best on higher, clean power. Why invest in a quality speaker and not properly power it to realize its full potential?
If you do decide to power them with your vintage Marantz, suggest you do not crank the volume and force the receiver into clipping. Low power often damages speakers far more than higher power does by the user forcing the amp into clipping. Good luck on what you decide.
Look at it this way. Watts are very cheap now compared to what they were in the seventies. Most speakers back then were highly efficent, 8 Ohm designs and could thrive on the 30-40 watt receivers that were common back then. Not today. Watts per channel have come way down and most speakers are designed at lower impedences to suck up this power. The 685 has a sensitivity of only 88 db and while it is a nominal 8 Ohm speaker, it has impedence dips of 3.7 Ohms. This means it will thrive and performs its best on higher, clean power. Why invest in a quality speaker and not properly power it to realize its full potential?
If you do decide to power them with your vintage Marantz, suggest you do not crank the volume and force the receiver into clipping. Low power often damages speakers far more than higher power does by the user forcing the amp into clipping. Good luck on what you decide.