You just need to write the attack a bit different, like this:
./hashcat --stdout -a 6 small_wordlist.txt ?a?a | ./hashcat -m2500 bla.hccapx -w 3 --status --status-timer 10
./hashcat --stdout -a 6 small_wordlist.txt ?a?a | ./hashcat -m2500 bla.hccapx -w 3 --status --status-timer 10