I have the Bernafon Chronos 9’s from Specsavers and the android ready SG 3.1.
First off there is indeed a special program for the SG music and for the SG telephone which can be adjusted from Bernafon’s Oasis. I do this with a HiPro connected to the PC over the COM port (serial connection) and CAS44 cables to the hearings aids. Works great, but I actually didn’t change that much to the amplification of the frequencies. I think I only generally adjusted the volume +3dB. If you wanna play with your Juno’s try to find a really friendly audiologist willing to part with this obsolete part of equipment (I stumbled into one after making their life hard by demanding to be able to play piano with only my HA’s.) or be willing to part with 400$ on ebay for and USB-HiPro and cables. The cables are rather brand and model specific so be sure to get the right ones.
Secondly, the android app is mainly there to allow you easy access to volume and program control. Next to those you can configure the behaviour of your SG3.1. (My personal choices are to turn the lights and the auto-call button off.)
Thirdly, probably most importantly, every mp3 sounds like crap. Thin sound like from the radio. With 4k€ headphones you apparently need lossless audio in your mobile. I have been listening to FLAC-files for over 8 months now and rediscovered listening to music! It’s great.
Lastly, you can easily get louder sound by setting the pre-amplification of the equalizer of your audioplayer to +5dB. This should also be able to increase your low frequency amplification.
My personal choice has been AIMP for FLAC playback and preamp, but that is strongly motivated for stability sake on an older android phone (v2.35).