Hello! My name is Jeremy, new to the forum. I just bought my first Roland, a Juno DS88. I have noticed a couple anomalies and I am wondering if they are normal.

First, there are some variabilities in key sensitivity. The most notable, and the one that brought it to my attention, is in the area of C-above-middle-C. The C is hot, slightly hotter than the other white keys around it, while the two black keys, C# and D#, are lower in sensitivity than average. So, if you hit the C and then the C# with equal force / velocity, you get noticeably louder output from the C. This seems to be present across many patches, though some patches display it more obviously. The default Grand Piano DS sound is a good one to hear the issue. There are other keys where I can hear different sensitivities as well, less obviously though. Is this normal, or is my unit defective?

Second has to do with scratchy noises. I first noticed it in Super Wurly. If I'm playing a G chord with both hands, and then hit the C-above-middle-C or the D with some force, I hear a little scratchy / breakup / distortion sound. This too is noticeable in other patches and keys, but that one seems to bring it out. It seems to do this at lower volumes too, but I don't think it does it in the headphones. I have a theory on this. I have it connected to a set of 66 W RMS powered speakers with 4" woofers via RCA speaker input jacks and an RCA-to-stereo-headphone-jack adapter cable to the headphone output of the Juno. The cable is connected correctly as the stereo effects are working right. It seems as if the cracking sound comes with the keyboard volume up high, even if the speakers and overall sound level are low. I think the problem goes away if the keyboard volume is below the middle and the speakers are turned up louder to achieve similar or even louder overall sound level. Make sense? So I'm wondering if the headphone jack is overdriving the speaker amp input stage thru the RCA input jacks, like a gain being too high early in the chain. My understanding of the various types of jacks and their typical levels and impedances is not very good. Does this seem likely? Or something else?

Thank you!
Jeremy