Hello!

I encounter this strange behavior with my not even 2 years old Fireface UC:

Sometimes the audio playback is really pristine and loud enough to trigger the limiter on my studio monitors (Eve audio SC207) at a specific output volume in totalMix.

But other times I realise that the sound is really compressed, lacks punch and details in the high end spectrum. Also the transients seem squashed and the volume is quite lower at same settings in totalMix. This happens using the same settings in the audio interface's control panel (sample rate 44.100, hi gain on line outup). When it sound ok I don't even need to set the line output level to hi gain in order to get a quality audio output. But when I feel it doesn't sound that good I feel that I need to set it to hi gain in order to get the kick to punch. I don't think is usb related because this happens even when I use the audio interface as standalone. I can feel it in the tone of my keyboard also. At first I thought the monitors had some problems maybe due to their dsp processing. But I've tested them with the audio interface from the elektron digitakt and they seem ok. Also I tested the fireface headphones output and had the same feeling. When I set it on hi gain and use my sennheiser hd 25 I can barely pass -20dbfs on metter without feeling that they are loud enough ( this is when the fireface seems to work ok). When It has problems I feel like cranking the volume much more than before, and even though the sound quality is not ok. It happend when I played in clubs sometimes. There was noticebly difference between my traktor set and cdjs even though I use only wave files and very well mixed tracks.

Did other of you guys encountered such problems? And if so, do you think the problem is related to the power supply? I really love the interface but is driving me crazy with this inconistencies. It really kills my studio sessions and dj sessions also. I started measuring the voltage on outputs with a multimeter by generating sinewaves at certain frequencies. I've also measured the output voltage from the power supply, but it seems stable at 12.0, 12.1 V... I didn't find any solution to properly test this but if some of you have other ideas please help me with this!

PS: I work as a software QA engineer. If someone can give me some guidelines how to test this strange behavior I am more than sure that I can come with some detailed results.