DAC + ADC Pro - jumper J4, volume setting

Hi there! Thanks for having me here ;-) 1. J4 The J4 description says its for balanced and unbalanced input. What do I ve to set where to use the j4 pins instead of the stereo input jack? Any HW configuration, jumper or software settings necessary? Or just to connect J4 pins 2 (R+),3(GND),5 (L+) to my input selector output? 2. Volumio powering up volumio give me a 100% volume until the end of the startup procedure when it finally goes to the software pre-set 25% volume on startup (volumio config). That said the mixer control is set to HW in the configuration. Any advice how not to blow the speakers every time the thing powers up? (And yes aware of the workaround to power up the amp after full boot procedure; but that's quite an ugly solution) Thanks for your help! Best