I do not have your exact situation and my advice is clearly worth what you paid for it but I am not sure you will hear a difference. I have several powered subwoofers and find the sound quality using the speaker level connections sounds infininitely better than with an unbalanced cable connection. I get a mild humm with unbalanced cables. With speaker level cables, that always goes away. Same thing happens with my power amp between unbalanced and balanced cables. Rel even recommends using speaker level inputs first.

The second point is that in wire runs under 25 feet, shielding on speaker cable should have minimal impact regardless of cable format, but particularly speaker cable and balanced cables. With balanced cables, because the ground is separate, any normal, shielded XLR cable should deliver perfect sound so long as it is an adequate gauge and made from oxygen free copper.

You should be fine using either cable type and I would suspect you won't hear a difference. The only exception would be that there(at least according to Crutchfield) is no official standard in XLR connections and you should double check and make sure that the positive and negatives are on the same side. Most consumer and pro audio uses the same design but every now and then a manufacturer will reverse the positive and negatives. It is uncommon but does happen on occasion. A reviewer on Crutchfield returned a pre/pro because his power amp had positive and negatives reversed. If they are reversed, you would have to have a custom cable made in which case it would be much easier to use the speaker wire.