Mark V 90W - Reverb Noise with Loop Hardbypass

Hello All,

I recently picked up a new Mark V 90w after waiting for over a year! I love the amp much more with the extra head room and separate channel 2 for crunch over my 5:35.

My issue at the moment is when the amp is set with the effects loop switched to hard bypass. With the channel 1 reverb set to about 50% (noon) or higher and when activated with the footswitch, there is quite a bit of noise hum/hiss. However, when I flip the switch to activate the effects loop (with nothing plugged in), the noise from the reverb goes down quite a substantially. Is this characteristic of the amp or do I have an issue? So far i checked to make sure the RCA cables are seated properly and they are. Any other tips?

Thanks

Edit: Added info

You get it sorted? Try the reverb send tube, forget which one off of top of head, probably v5 maybe?