I know REL hum has been discussed, but seems like it’s usually from the High-level speakon connections…
I’m getting hum from both of my brand-new REL T/5i subs through the RCAs. Hum reduced when crossover frequency is lowered. it’s not bothersome when music is playing, but it’s noticeable when music is paused/silent.
When amplifier is off, hum is still present, but lessened.
if I disconnect the RCA cables, the hum goes away.
RCA cables are not cheapies, but not esoteric ones. Run is fairly long tho, like 20 feet.
I did NOT get hum with my Cambridge MINX subs. (Nor did I get hum when I demoed some SVS subs.)