Upgrade from C-J MF2100 to MF2250?

I can not comment directly on your question concerning the 2100 to 2250. But I did experience upgrading from the 2500 to 2500A and it was a substantial upgrade. I would expect you would experience the same thing assuming the rest of your system is of a high enough calibre to resolve the difference. The "A" mod made the amp more detailed with cleaner transitions especially noticable in the mid to high frequencies. The unit did require about 50 hours of break-in after the upgrade. Hope this helps.

Thanks, Chuck