Looking at the Q5s myslef...and been searching for the answer to this question.
I have a BTR3 and its EQ works in BT and DAC mode. (the "better" BTR5 model, the EQ does NOT function in USB mode)
I also have a Alpen 2 E17K which is my DAC for my fullsized Vmoda headphones, it has simple Bass, Treble adjust with its LCD screen.
If only they have made a newer/better version of the E17K, cause having on board digital steps to adjust both Bass and Treble on the fly, is what i want.
To answer yours and Marco question, yes the EQ settings are saved on the amp and you get your EQ'd sound thru any source. I set settings on my LGv30 Fiio app then played music thru UAPP; settings stuck. Then thru Tidal bluetooth on same phone, settings same. Then switched to iPhone and played tidal thru BT, settings same. I then went into the FIIO app on the iPhone and saw the EQ was set to the same wild settings (for testing purposes) that I had done on the Android so its clear the settings on are on the amp.