I was playing around with the external input on the Sub and, while it sounds fine when I connect my Waldorf Blofeld directly, it’s completely distorted when I route something from Ableton Live to the Sub using the External Effect device. I need to reduce the output gain to -20dB or lower the input volume on the Sub to maximum 2 to eliminate the distortion. Other external effects (like a talkbox pedal and a digital delay) work fine from the same output with no gain adjustment. My soundcard is a Presonus FP10.
iPod at max volume => Sub. No distortion until 2, which is supposedly normal and should be fixed by the next firmware (1.3.0 was deleted).
iPod at max volume => FP10 line input with no gain => FP10 line output => Sub. This gives me the same effect as 1. However, in Ableton Live, the input shows up as -24dB.
The bottom line is : Sub’s input sounds fine with “raw” line input, but distorts anything that goes beyond -10dB. All that below 2 on the Sub’s mixer. Is this normal? Can anybody try feeding a 0dB signal (any song really) from Ableton Live to the Sub?
Anyway, this is not a problem. Any piece of audio gear that has to accept levels from various sources has to deal with the fact that sources from dynamic microphones to pro audio line levels can swing over a range of well over 30 dB and need to have gain controls to account for this.
You already know you need to reduce the levels when using the FP10 to drive the Phatty, so do it. Insert a Utility device in the Live effects chain to control the gain without using the channel slider if that is what is bothering you.