Dunno, just google-image search for "daw studio" or so - look what their software looks like
https://www.google.com/search?tbm=isch&q=daw%20studio&tbs=imgo:1Think most of them use some kind of "gray" or slightly tinted (cobalt + gray) background (I prefer "titan"-gray) + some metallic or black-plastic style buttons, knobs, sliders. So they intimidate a "real world device" rather than "software".
You will also recognize, that they split "panels" visually. While you have these red header bars, the content below gets no "border" around all widget groups. The "Visualization"-boxes have borders but the slider-groups not. Imho it misses bit of "contrast" to group things.
So maybe look at google images for "daw screenshot" and see how they do things there.
As for your toolbar the flat look removes a lot of contrast - it somehow needs something else to distinguish it as "clickable buttons" rather some kind of imagestrip.
Scaling: look at the sliders for "loop" and "repeat", now check slider marks - there are some thicker and some lighter ones - I first thought it is some kind of "START tick tick TICK tick tick tick MIDDLE tick tick TICK tick tick END" thing but it seems more to be based on some scaling issues. Imho widgets should not scale in most cases but rather loose "details" (so show less "tick" lines in this case)..
Best thing is to have widgets either scale "step" wise (so lines keep consistent line heights). Else you need to do some kind of bilinear filtering which allows "subpixel-scaling" but this then of course only, if scaling gets used in multiple spots of the app (it would look very odd if 99% is pixel crisp/sharp and then there is this one widget looking blurry).
@ loop / repeat
The top portion seems to be some kind of "button" to enable/disable the functionality? With that flat look it could also be some kind of "header" (similar to the red headers like "display" and "fx"). If it was a header, it would look inconsistent to Volume's "In | Clip | Out" sliders). If it was a button I would suggest to use some kind of "on off" indicator. It is a "switch button" and needs to either get tinted when "active", receive a "pressed/sunken" look (not possible with flat) - or my suggestion: you prepend a small Rectangle before the text: it is dark green when disabled and a light green when enabled (like a LED/lamp glowing).
@ Colors
You could think of using different colors (hue or brightness) for captions and values. So a "1.0" below a slider is a bit darker (between widget "tick line" gray and "caption gray").
The icons below the wavetables appear way brighter than the texts - imho in the screenshot they look like "look at mee!!!!!". The clickable icons of the toolbar (first 2 ones) have less contrast than the wavetable-symbols.
Edit:
I am talking about the first screenshot. the "on off"-switch button could design-wise become similar to the shortcut-indicator-triangle seen in the bottom of the third screenshot.
bye
Ron