So what have been used is the two applications Audio Evolution and the USB Audio Recorder OTG USB Cable and one USB Soundcard ( M-Audio Fast Tracker 2 ).
There is some faults of mine regarding the sound-
The guitar got recorded with a direct line and the trombone and ukelele was recorded with a Shure SM 48 a Dynamic microphone. ( The telephone being used was a Samsung Galaxy S3 ).
So directly there is a disparity in the recording as the guitar have no natural ambience in its sound as do the other two instruments also to record natural instruments with a dynamic microphone is in general a bad idea. ( but you use what you have, right? ).
The only production on the recording was the Audio Evolutions built in effects-
Which was some reverb on the guitar and some compression and a little bit more reverb on the master track to make the things gel together a little bit.
So here is the recording.
Recorded the guitar without no problems but when it was time to record the ukelele it got buggy and did not want to record so in the end had to mixdown the guitar to a wav file and start a new project in the Audio Evolution app and then it was not any problems with the recording but got some other problems like it seemed that there was an auto gain feature being activated even though it was not supposed to be and could not get any control over the input volume ( which I had recording the guitar ).
So what happened was that the trombone got distorted and being on some kind buggy auto gain it did not matter how far the microphone got placed except weirder sound because of the room ambience...
It also crashed a couple of times.
Yes it did feel unstable.
To be honest the Audio Recorder PRO is still in BETA and what the developer have accomplished even with these problems are truly remarkable as with some patience and a better microphone you have a very portable studio as the USB Sound Card uses the battery of your device and this without latency and depending on SoundCard up to 24 Bit sound with direct monitoring of your audio signal.
I can not say yet and will have to record some more but as I have recorded my guitar many times into the same Sound card into the P.C and it does sound the same to me.
So if you have a USB Sound Card and a OTG USB cable and a telephone that can handle it.
It is the only way you are going to be able to get a professional recording made with your Android Device.
And if you are not interested in multi track recordings you can use just the USB Audio Recorder PRO for one track recordings.
So To finish would say that the possibilities this offers is exciting but would not count on it in a critical situation yet.
But for recording in the park or not wanting to bring a computer for recording or as a backup if your computer breaks down as at least you have the possibilities to continue recording with the same audio quality as your USB Sound Card would allow.
Spoke to the developer and he said that it sounded strange regarding the auto gain and that he had ran into the same problem also with a Samsung Galaxy S3 and that it is probably the cable that got loose and that things got recorded straight in with the microphone of the phone.
Well that would make sense and had been thinking that it could have been a reason.
Especially because of how much more sensitive the microphone seemed to have gotten when the recording got made with the trombone and not with the Ukulele...
Well in future update there will be a warning built in if the USB cable gets detached.