from B&w 805's to Usher be-718 - what to expect?

I would think you'd at the very least hear a very big improvement in bass weight and extension since this is an area of strength for the Ushers and not so much for the 805s. That said, I don't think the Ushers will open up and sound their best with 100wpc as many reviewers have stated they really need/appreciate more power to show what they can do.

That aside, I would think something like Silverline 17.5s could offer a significant upgrade and work fine with your amp. Best of luck.

I have to agree with Soix, although I think the improvement over the 805's is in more than just bass weight and extension. You can take that with a grain of salt if you want since I am an Usher dealer. But, being an Usher dealer I will also confirm what Soix said as well about the power. 100 wpc is not enough, in my opinion, to show what the BE-718's can do. There are other speaker options that would match better with the power of this amp.

I use Jeff Rowland Concerto Integrated (250w - 8 ohm), Weiss DAC2, Audioquest Sky, Volcano and NRG-5 cables, Fisch AC passive filter and an Aavik rack with Nordost Pulsar Points and to me the system sounds fabulous. I tottaly recommend the JR for Be-718 - great damping factor, very dynamic amp with lost of power. The Be's seem to open up only when fed lots of power. Without great wattage they sound dull. Try to meet the requirements and you will be rewarded. Cheers.

Haven't heard the 718's but I have had a pair of 805's( N not S). They were replaced by a pair of JM Labs 907bes. The improvement from top to bottom was huge. Detail without brightness/harshness, warmth in the mids and deeper more controlled bass. 907's pop up occasionally and they are a steal, they were a limited edition replaced by the Electra 1007be series. I haven't heard those but they should be easy enough to find for an audition. I only sold the 907's to get their bigger brother the 927bes which I still have and will not part with, fantastic speakers. Fond memeroies of the 907's. Good Luck.