Massive distortion/crackling with Cubase 5 on Mac and external USB audio interface

Hi guys,

this forum is my very last resort after going through each and every FAQ/support guide/audio interface support teams…

I am using a Mid-2011 21.5" iMac with 2.5 GHz i5 CPU, 8GB RAM, macOS High Sierra (highest I can upgrade to with this machine sadly) and experiencing massive problems with external USB audio interfaces and Cubase Studio 5.5.3

I first tried with a Focusrite Scarlett 2i2 3rd Gen, now a Mackie Onyx Producer 2x2. With both systems, installation and configuration within macOS and Cubase worked perfectly. However when I route my VST connections to the audio interface, the signal is output with a HUGE distortion, as if the output gain was set way too high.

This happens as soon as the Stereo Out fader is JUST above the bottom position, with the interfaces’ monitor gain turned low as well as the monitor gain. The distortion must be going on somewhere between Cubase/Core Audio/Interface.

I have already tried the following steps:
-Change buffer sizes back and forth
-Change sample rates back and forth
-Try various combinations of the ASIO driver settings (Multi CPU usage etc.)
-Restart system
-Try different USB ports on my iMac
-Reset the macOS audio config files (recommendation of Focusrite support)
-Install the Steinberg “CoreAudio2ASIO Patch for Mac OS X 10.7 (Lion)”
-Try Cubase 10 demo version -> Steinberg downloader not working on macOS 10.13…

What I did notice is that as soon as I also set up the interface’s two input channel in VST connections, the “audio activity” and “audio clipping” indicators on the transport window instantly turn red without any input signals coming in. At the same time, the CPU usage percentage in macOS is moderately low.

I am absolutely lost on this issue and think that I have gone through all of the obvious steps and beginner issues. I feel that this is an issue with using Cubase 5 together with macOS 10.13. This would be pretty bad because I currently don’t feel like buying an expensive new machine and Cubase license.

If anybody on here could point me to an idea that I haven’t thought of yet I would appreciate that a lot!


Hi mate,

Not 100% savvy on cubase but thought to throw another idea to you.
Have you checked all cables and their connection? A broken solder could be your issue??
Just throwing it out there :upside_down_face:

Good luck mate