Fender HRDx Effects Loop Question

[jazztastic]

Splitting this conversation off from my other thread.

I primarily use the effects loop in this amp to attenuate with a volume box.

Question: If there is an issue with one of the IC's (U1,U2 or U3 - TL072) does this affect the actually sound quality of the amp as well as channel switching, reverb etc. ?

[g1]

U2 is in the switching circuit, so it won't affect the sound. U1 is in the FX loop, so it can only affect the sound when using the loop. U3 is in the reverb circuit so it can affect the sound unless the reverb pot is at 0.
A gross fault in any of those IC's could pull down the low voltage power supply and cause other issues.