Bass and Treble is +/- 6db @ 85 Hz and 6.5 kHz where the Q-Faktor can also be parametrized.
Pls check chapter 8.4 of the handbook:
"The simpler form of EQ has been the Bass and Treble controls as they are found on any ‘standard’ HiFi stereo amplifier. They easily and quickly allow to modify the sound to your personal liking (more or less Bass, more or less Treble, obviously). An even more useful application is to quickly change the amount of Bass / Treble in smaller quantities so that music compilations don’t have one song making the cones fall out while another one makes you think that really happened. Producers and mastering engineers not only have their own taste, they also sometimes fail in providing a mix that is on an average sound level compared to others. In that moment a quick turn on the two ADI-2 DAC’s small encoders will make the music sound perfect.
These Bass and Treble controls are limited to ± 6 dB. Everything exceeding such values should be handled by the EQ, and/or calls for better speakers/phones. The corner frequency and quality factor of Bass and Treble is user-adjustable in the display’s menu, making this feature even more useful. Adapt it to meet your speakers/phones or your personal taste – it will greatly improve your pleasure in listening to music again."
I personally have a permanent bass enhancement for +3dB on my DAC in front of Accuphase E-600 / B&W 803D3 which is sufficient for my usual listening levels when watching TV or movies.
Dynamic loudness is active as well to keep the sound at this level even when turning down the volume.
IMHO +6db is already quite a lot and should be noticeble. Otherwise you can decrease the Q-Factor from 0.9 (default) to i.e 0.7 or 0.5 and boost already at 100 Hz instead of at 85 Hz (default). Alternatively use the PEQ.
Look here what +6dB are @Sengpiel: http://www.sengpielaudio.com/calculator-levelchange.htm
"Double or twice the loudness = factor 2 means about 10 dB more sensed loudness level (psycho acoustic)
Double or twice the voltage = factor 2 means 6 dB more measured voltage level (sound pressure level)
Double or twice the power = factor 2 means 3 dB more calculated power level (sound intensity level)"
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14