Hi folks

I recently bought a second hand arcam alpha 5 plus cd player and paired it with an old denon pma255 amp i had in my garage and a pair of £150 mission speakers.

This is very much a system thrown together from what i had lying around at home and i use as my second system in my spare room. Now looking to improve partnering. Was looking to upgrade the amp first then speakers. Any suggestions on the amp? - looking to spend upto £300/$450 second hand or new.

Thanks