they should both sound good!
I am running single ended so did not get the reference you'd made to the ch800s. I know zip about them.
but an after market cable will open up the high end of the LCd3s some. many report a general "lifting of a veil" they didn't know was there. that was my experience.
conversely, people go with after market cables on the hd800s to tame the highs a bit and for overall improvement. but as I said, I don't know the ch800s and it may be doing the trick for you already. certainly nothing to rush into. I used my lcd 3 default cables for a year happily before they failed. the I found both Q cables and Charleston cable company cables to be a very noticeable improvement over the originals.
enjoy!
oh, what's the rest of your path" (dac, amp and such); and are you playing high resolution files or analog or cds or mp3s or streaming or )?