When inserting a plugin (especially a 3rd-party VST3) onto any channel while input monitoring is active at low buffer sizes (32, 64, or 128 samples), Nuendo 15 immediately produces crackling, pops, and audio dropouts — as if the buffer size were too small to handle the current load. The only workaround is to manually switch to a different buffer size and then switch back to the original setting. This resets the audio engine and resolves the issue temporarily.
This behavior was not present in Nuendo 14 and appears to be a regression introduced in Nuendo 15.0 that has persisted through all subsequent minor updates.
System Configuration
• Software: Steinberg Nuendo 15 (all minor updates, issue present since initial 15.0 release)
• OS: macOS (latest)
• Hardware: MacBook Pro 16” – Apple M3 Max
• Audio Interface: SSL 2+ MK2 (CoreAudio driver)
• Buffer Sizes affected: 32, 64, and 128 samples (all tested – issue is not buffer-size-specific)
Steps to Reproduce
- Open any session in Nuendo 15
- Set buffer size to any low value (e.g. 64 samples) via Studio → Studio Setup → CoreAudio
- Arm a vocal track for recording, enable Input Monitoring
- Insert a low-latency 3rd-party VST3 chain on the track (e.g. EQ + Compressor for real-time headphone monitoring)
- While monitoring is active and running stably, drag any additional plugin onto the Master channel (or any other channel)
- Result: Immediate crackling, pops, and audio dropouts begin
Expected Behavior
Adding a plugin to a running session while monitoring is active should not destabilize the audio engine — especially on high-performance hardware like the M3 Max, which is capable of handling significantly larger sessions without issue.
Actual Behavior
The audio engine behaves as though the buffer is overloaded. The dropouts persist until the user manually:
- Switches to a different buffer size (e.g. one step up or down)
- Switches back to the original buffer size
This forces an audio engine re-initialization, after which everything runs stably again — with the exact same plugins and session load as before.
Additional Context
• The issue occurs regardless of whether the buffer size is 32, 64, or 128 samples (maybe even every buffer size, but I usually stay below 256 for recording)
• The issue is not present in Nuendo 14 (to the best of my knowledge — this appeared with Nuendo 15.0)
• The issue has not been fixed in any Nuendo 15 minor update to date
• The same workflow (dragging plugins into a live session) works without any issues in three other DAWs used on the same machine with the same audio interface — confirming this is a Nuendo-specific regression
• ASIO Guard is not a viable workaround for this use case, as it introduces too much latency for real-time vocal monitoring with a live plugin chain
Impact
This is a significant workflow disruption during vocal recording sessions. Every time a plugin is added during tracking, the engineer must interrupt the session, navigate to Studio Setup, toggle the buffer size twice, and return to recording. For a professional post-production tool at this price point, this level of instability during a core recording workflow is unacceptable and urgently needs to be addressed.
Please prioritize a fix for this regression. Thank you.