Just anecdotal, but I upgraded last year from a MF A5 integrated to a used Luxman L-509x just over your budget.
Current speakers are ATC SCM11v2s and there was a noticeable upgrade to the sonics going from the A5 to the 509x.
Current speakers are ATC SCM11v2s and there was a noticeable upgrade to the sonics going from the A5 to the 509x.