I would like to share some of my experience with the RME Babyface as a portable recording device.
I use it with an ipad mini and an external battery with 10.000 mAh and it took me a while to figure out what causes the problems that I experienced.
CLASS COMPLIANT MODE:
Running the Babyface in CC Mode works as long as there is enough power for it and sometimes it's not obvious that there's not enough power for it. The Babyface might seem totally normal, and the LEDs are working as they should but if there are some problems regarding power (power peaks) - the program you work with on the ipad will start to act weird.
I work with Auria as my main DAW on the ipad and insufficient power can result in wrong timecode, slow recording, crackles, blackouts during recording and the ipad might unmount the Babyface from time to time.
As every setup is different I can only speak for my 10.000 mAh battery pack that i had bought on amazon (easyacc -27€) but it might also happen with other battery packs. This one has two USB connections - one labeled with 1A and one with 2A.
First of all, I can use the Babyface in CC mode with microphones that don't need 48 Volt Phantom Power (dynamics + ribbons) running from the 1A USB output of the battery. This works flawlessly!
Phantom Power nevertheless caused problems and even using the 2A USB output did not help. Auria was unstable and in the end unusable - sometimes it worked for minutes but everything acted weird and I had lots of problems. It might seem that the problem is Auria or the ipad but that's not the case - the problem are power peaks.
So I bought a USB Y-Power adapter cable (see picture) to connect the two usb ports of the battery (2A and 1A) at the same time. I connected his Y-Cable to the Y- Cable that RME provides to power the Babyface. Now 48 Volt mode on two channels is possible without problems!
STAND ALONE MODE
Stand alone mode is an amazing feature. With an external recorder (like a Zoom H1, H2 or others) you can record two microphones (using the RME preamps!) and record the signal via the line-in of the recorder. This is the smallest setup I ever had to record audio in good quality. It doesn't need as much power as CC Mode but you can also run into problems when using Phantom Power in stand alone mode:
1A battery output connected to Babyface:
With 48 Volt engaged I experienced high pitched noises that are connected to the flashing LEDs of the Babyface. Every time there is some signal
that makes the LEDs light up there is a high pitched noise that is added to the signal. You have to listen carefully as it's only added if there is some sound and you might not hear it when there is silence. You can help yourself by selecting "OUT" on the Babyface and reduce the level to the minimum so the LEDs won't flash at all or you change the power connection to the 2A USB plug of the battery. I recorded the line signal from the phones output to feed my external recorder, so i didn't need the "OUT" to have any level at all.
2A battery output to Babyface:
No problems with 48 Volt Power. Enjoy!
In general: Once you set the levels for the input source at the Babyface - switch to display the output that you don't need (phones or out) and reduce the level to a minimum to have no flashing LEDs. This should prevent noises even if the power drops.
I hope I could help some of you. I'm absolutely amazed by the new possibilities of the Babyface and I can't wait for the Totalmix FX APP!
PS: RME - if you still need some beta testers for the Total Mix App you are highly welcome !