Best cable to use with meridian 508.24?

Try Acoustic Zen Silver Reference or Harmonic Technology Prosilway II or III. Either cable works well. I'm sure they're many others. Everyone has their favorite. But synergy is the key and I know from experience these work well with your equipment.

Meridian uses Van Den Hul cables. I really like the JPS Superconductor interconnect. It lists for about 300. It sounds very natural.

I use Harmonic Technology Prosilway II XLR balanced ICs with my 508.24 into a Krell KCT with excellent results. Very evenly balanced overall with great air and superb dynamics and tight, extended bass.

I found the Stealth M-21 Special is the best source cable and it will fit in with any preamp. Second choice is home made which is better sounding than my 3 choice Audio Note AN-Vz. Forth choice is NBS signature but a bit too tight to my preference. Fifth choice is AZ Silver Reference. Lower frequency response is too loose and the high is not as extended as all the above.
To me, source cable needs to be as accurate as possible.

However, your preamp to amp cable is very important too. I use NBS King Serpent or my home brew as 2nd choice and AZ silver reference as 3rd choice and Synergistic Designer Reference as 4th choice.
To me, preamp to amp cable needs to be open with wider bandwith than the source cable.

My friend prefer NBS to NBS but it sound a bit "Solid State" harshness to my ears. Very Clean though.