MC275: do you use RCAs or XLRs? Why?

I'm researching preamps for my McIntosh MC275 Mk IV and need to decide whether to buy a single ended or a balanced out pre. Do you use RCA or XLR inputs, and why?

From looking at the schematics it makes sense to use the XLR inputs to avoid V1 tube and the volume pots. Yet I've been exchanging with one user who tried that and preferred the RCA inputs (with a Lamm LL2), even though he owns several XLR and RCA pres (lucky!). Right now my Rotel preamp only has RCAs so I can't compare, and auditioning options is not posible where I live...unlucky!

FWIW, some SE preamps under consideration are First Sound Presence, Lamm LL2, Joule-Electra LA-100 or 150, Herron. Balanced pre considered is Atma-Sphere MP3.

Thoughts?

Thanks!
Horacio