RIP is passive so I don’t think it’s possible for it to generate any kind of tone. All it can do is modify whatever you plug into the ins.
Sounds like you have noise somewhere else in your system that you weren’t hearing before with a different output solution.
Does the noise persist when you unplug the 1/4" cables from RIP? If so it’s your mixer/soundcard/speakers.
Does the noise happen when 1/4" is attached, but nothing connected to RIPs 3.5mm inputs? Sounds like noisy ground in your modular case - try the ground lift switch.