@joekapahulu Acurus was a great value version of Aragon, but cut some corners to keep the prices modest. There's a good chance that a better preamp would be a huge upgrade, whether it be SS or tube. For example, many top models have separate power supplies connected by an umbilical.
You could research what other owners of MC250 have found synergy using...guessing their replies will be heavily numbered towards Mc obviously.
This is far from the first time similar questions have been asked. You have a lot to gain searching archives for those threads and then ctrl-F "MC250". Cheers,
Spencer