[PROBLEM] Pi 4 with Boss DAC 1.2. New user

[Leviathan]

Hi all
Only had my Pi 4 for a couple of weeks and everything is new to me.
In this time, I started using another well known software and have been trying Moode for the last week or so.
Have also just changed from a Dragonfly Red to Allo Boss DAC.
So apologies for these questions which I am sure are “old hat” for many, but not for a new user;
1) re EQ. in basic terms, how does “off” differ to “flat” curve?
2) when EQ off, my output rate stays same as decoded rate i.e. 16bit. When EQ on, output rate jumps to 32 bit and I have no idea why. 
3) Allo Boss uses Burr Brown chip. I am given 4 options under ‘chip/device”options and have no idea what any of these mean. “FIR interpolation with de-emphasis” is chosen by default. Are these options related to Moode operation or should I be looking elsewhere for answers?
Thanks to all. Very much enjoying using Moode so far, although am struggling a bit with the Library/playlist functions.

Try each of the filters in turn and listen to the difference, if any.

Also try Sox 32 bit / 384 kbps (at the various quality levels) and determine which sounds best to your ears with your amp and speakers.  A 384kbps input signal to the TI 5122 DAC on the Allo Boss will bypass the on-chip interpolation. Many report that it sounds better than the on-chip filters.

And report back with your results.

Phil

Thanks for taking the time to reply. Please see above reply re initial thoughts after trying the 4 Burr Brown chip filters.
Re SOX, I have tried the suggested 32 bit/384 but am struggling to hear any significant difference between this and leaving SOX disabled.
I need to do two things though. First, some serious listening with music more suited to revealing differences. 
Second, do a bit more reading on the subject of digital filters, up sampling, etc. From all that I have heard/read over the years, I am still struggling with the concept that anything can/should improve the sound of (say) a redbook CD at 16 bit/44.1 KHz. I have for so long subscribed to the belief that you cannot improve/replace what isn’t there in the first place, that it’s going to take some serious persuasion for me to change my mindset. I am always open to new ideas though!