I've been a bit confused by the meters in some of my plug‑ins and in Cubase. They sometimes go red, which I presume means that they're clipping, but I can't hear any distortion. Is this a problem — by which I mean, are the plug‑ins doing anything nasty to the audio that I can't hear, and do I need to bring the levels down? The same thing happens on my channel meters in Cubase.
SOS Reviews Editor Matt Houghton replies: Hmmm... I'll have to say maybe, and maybe not! The first thing to point out is that in a modern DAW environment such as Cubase, there's no reason why the computer can't handle audio that goes above 0dBFS throughout the signal chain, as long as the level is brought back down again prior to it being mixed down on the master stereo bus. In Cubase itself, you can quite happily have individual channels going over 0dBFS and the master bus will still sum them perfectly happily. A 32‑bit floating‑point engine (or, better still, a 64‑bit one) as in Cubase, will happily compute much larger sums than are needed. That's the good news.
The bad news is that not every plug‑in is designed perfectly, and those that work in a fixed‑point environment may not cope so well. Also, plug‑ins that model the behaviour of analogue hardware aren't always designed to give of their best when the input signal is way beyond what the designers intended the plug‑in to be used for. Certainly, I've heard sub‑optimal sounds coming through some not‑inexpensive plug‑ins when hot signals are run through them.
As you say that you can't hear any problems, then, quite frankly, it sounds like there's no major problem. Do make sure that you're checking on decent monitors (or, better still, for this sort of forensic detail, good open‑backed headphones), because if your monitoring environment leaves something to be desired, you can't really be sure that there's no distortion.
The best long‑term strategy you could adopt to tackle this possible problem is to avoid it in the first place. There's absolutely no need to use such hot signals in Cubase that this question will arise. It's always tempting to look at the Cubase meters and think that they look very low — but remember that these are peak rather than average meters. With 24‑bit audio (and even 16‑bit), the noise floor is low enough that you can afford to leave plenty of headroom on every channel. Aim for something like ‑12 to ‑18 dBFS on a kick‑drum or snare track and build the mix relative to that reference. You should find out that the 'problem' goes away — and if you throw so many things into the mix that it starts to get rather hot at the input of the master channel, try using the master channel's gain control to back off the summed level a little before you start applying any bus or master‑style processing. If you're worried that the track sounds quiet, turn up your monitors. If you then want to add any loudness processing to get the level of the final track up to more commercial levels, you can — and you'll probably find that it's easier to do so.