2nd on straightwire. I upgraded to their 2nd to top of line xlr cables and top power cord for amp, second to top for dac and pre. Not that expensive and a huge! improvement. Ultimately though replacing my solid state amp with with a BAT VK60 SE gave me exactly what you are looking for.
problem with the LS50 is it’s not quite high enough impedance at some frequencies for some amps, and they are brutally honest. I used them with an Ayre V5xe, an indisputably quality amp and did not like it. Not bad, just not mellow.
I also found the LS really shows what the pre is doing so don’t be surprised at the difference swapping out a pre.