Bullitt5094 6-25-2017Very true. Also, even with an XLR cable it would be highly preferable to choose a cable having low capacitance per unit length (e.g., no more than around 25 or 30 pf per foot, and preferably less), and to drive the cable with a component having low output impedance (e.g., no more than two or three hundred ohms or so, and preferably less).
I don’t think a 50ft RCA cable is a good idea.
However, given the several fine suggestions that have been made of suitably priced amps that provide only RCA inputs, I would seriously consider using one of those amps in conjunction with a Jensen transformer that would accept an XLR input and provide an output that would be connected to the amp with a short length of RCA cable. That may very possibly even work better than an XLR to XLR connection, because there is a substantial body of anecdotal evidence indicating that the sonic quality of the XLR input circuits of many modestly priced amps is inferior to the sonic quality of their RCA inputs.
A suitable transformer would be the Jensen model PI2-XR if a stereo amp is being used, or a pair of PI-XR if monoblocks are being used. The PI2-XR is available here for $250. (That page shows a PI2-XX, having XLR connectors for both inputs and outputs, but you can specify RCA output connectors after clicking the "purchase" link). Further details can be found at the Jensen site.
Good luck. Regards,
-- Al