I have heard many different cables with the Magico S and Q series (thought not with the M Projects). The best cables i've found for synergy are firstly Siltech Royal Signature series which are very quiet, harmonically rich, a little warm, have nice tone and timbre and sound stage well. Bass is very good. Build quality is excellent. These are a good choice if you want to augment the bass somewhat.
Secondly Jorma Prime and Statement cables. Jorma sounds natural/organic, smooth, mellifluous, resolving, well balanced top to bottom and harmonically rich. They are overall neutral, but have a touch of warmth. The Prime xlr's use Bybee Slipstream Golden Quantum purifiers inside the walnut barrel. They nail the midrange. The Statement sc's are very resolving, quiet, pure and have excellent sound staging. Essentially taking Prime to a higher level. Jorma told me just a single run of Statement sounds better than the Prime Biwires!
Finally Tara Labs Omega Evolution & Zero Evolution cables. Mighty big, mighty expensive. I recently heard a full loom of these cables with a pair of Magico S3's & Vitus SIA-025 and was impressed by the low noise floor, spacious sound stage, neutrality, smoothness, resolution and bass. Those qualities blew me away (as you would expect). They aren't as warm or harmonically rich as the Siltech Royal Sig's or Jorma Prime though, and the top model Siltech Royal Sigs bass is a bit tighter/deeper.
If I had to summarize the sound of these cables, i'd say Siltech = musical, Jorma = natural and Tara Labs = sophisticated. Any of the above cables would be an excellent choice with your M Projects imho :thumbsup: