I bought my BL18s about 4 years ago and added a BL19 about a year ago.  I've always used a Transmitter 1 to connect using WISA.  Yesterday I decided to use cables to connect them to my Core - Thanks Steve@ who got them to me within a couple of days.

I hope others may find the information below useful/interesting if they have some of the issues and thoughts that I have had.  The background to this is as follows:

My experience with WISA has been patchy to say the least.  When I just had the 18's they would generally start up ok albeit with a 20 second delay whilst the transmitter fired up and did its thing.  Adding the 19 made the start-up process less reliable.  The speakers could turn on and off several times during the start up process and occasionally everything needed to be powered off and on again - naturally this would happen when I was demo-ing to friends. I could work around this by just playing through the 18s at first then turning the 19 on (and flicking the 2.0/2.1 switch on the transmitter) but this was hardly an elegant solution.

Furthermore, at least once a day one of the speakers would lose its WISA connection and turn off and on again after about 10 seconds.  Whilst WISA worked well about 99% of the time the other 1% got pretty annoying.  I did try all the recommended fixes and moved other wireless devices etc etc but could never establish a flawless WISA experience.

From a sound point of view (as mentioned by others on another thread) I felt the sound processing between the 18s and 19 which is done by the transmitter left the mid-range somewhat weakened compared to using the 18s on their own.  Adding the sub made a real difference to the sound above about 60%-70% of maximum volume but to be honest I never really play at that level unless I'm showing somebody how the speakers sound played loud!  Below that sound level I preferred the 18s on their own with the stronger mids.

I'd always wished their was some way of keeping the 18s as they were but adding a little more depth to the low bass i.e. trying to find that low down rumble below the range that the 18s can go.

So I ordered a couple of cables from Steve@ and daisy chained my speakers as follows: Core>BL18>BL18>BL19.  There's no automatic high/low pass filters with this set-up.  With the transmitter I believe it is around 120Hz.  So I turned the BL19 low pass filter "on" and set it pretty low (about 50Hz from a possible range of 40-160).  I believe the BL18s go down to about 40Hz.  I simply used a lot of trial and error to find a level where the bass wasn't overwhelmed and only seemed to extend the range downwards.

I was prepared for the sound to be horrible but it isn't.  I actually like it more than when I was using the transmitter and the inbuilt sound processing.  After playing around with the LPF filter on the BL19 the sound is exactly as I hoped with the 18s sounding as fantastic as they did on their own with a bit of oomph at the very bottom of the frequency range below 40Hz. Obviously there is a trade off at very high volumes where the ABL kicks in on the BL18s and the BL19 isn't compensating for anything above approx. 50Hz but that's would be the case in any event with the 18s on their own and, as I said earlier, I rarely use them that loud as I live in an apartment and quite like my neighbours.

I will of course accept that sound is a personal thing but I can't think of any technical reason why what I've done is wrong (extreme audiophiles who employ gold-plated pixies to hold their cables off the floor will probably have some views).  And £2,500 might be a lot to have paid for a bit of extra oomph but I don't care about that because I like having a BL19.  The speakers sound great to me and I have eliminated those pesky WISA drop-outs.  Its also nice to have things start up instantly without the WISA delay.

Like some other folk I guess I cut B&O a bit more slack than I would other manufacturers when it comes to idiosyncrasies of their products.  I cant really explain why but its probably because their stuff looks so good and I love owning it.  But it is really nice to think that when I'm showing my stuff off in future it will start up cleanly and all speakers will carry on playing for 100% of the time.