I am currently running 2 meter RCA interconnects with adapters at the amp but was wondering if running XLR cables with an adapter at the preamp would offer any improvement.In principle, using an XLR cable with an adapter at the preamp is the better of the two approaches, in part because it would provide somewhat better rejection of hum and noise. It corresponds electrically to the configuration shown in Figure 2.1 of this Jensen paper.
In principle, using a Jensen transformer would be a much better approach, as suggested above and as described in the paper.
As a practical matter, and assuming that you do not presently have perceivable problems with hum or noise, whether or not either of those alternatives would provide an improvement in your particular setup is anyone's guess IMO.
Regards,
-- Al