Greetings y’all. I currently use my 6k’s with Xone DB4 via digital output, using Mogami 2965 Coaxial cables. Any suggestions & helpful tips on how to improve the sound quality via the extensive utility menu? Any hidden features that i should be aware of?
Thanking you in anticipation 
Split cue is buried in the menu if you need it, but there’s no way to override it except cueing nothing and just listening to the master in stereo. So, all or nothing when the setting is selected. It would be nice if cueing two channels at the same time would at least override it, but having a dedicated physical control would have been best.
The tone controls’ three modes have an influence on the sound of the mixer due to modeling the analog Xone’s respective phase distortions on their EQs and Isos. Think of the three modes as flavors. The DB4’s ‘dry’ tone is only in filter mode with the filters in bypass (low pass on top to full right, high pass on bottom to full left).
There are some useful settings available, like changing the stereo width per highs & lows and padding things like the headphone jack. Get familiar with the options in there. The stereo width stuff is intendend for installations and a big sound system, but it’s useful for tightening up Elastique’s bass if you match its corner frequency with the tone control setting. The later firmware added rotary mode, which I use exclusively on it. The dry-wet on the effects does lend itself to simply being relegated to the upfaders. There’s also some neat output routing options available.
The booth DACs are inferior to the record & master DACs, so just use the booth outs when you absolutely have to for a utility monitor when necessary. When possible, don’t use the booth if you care about preserving sound quality. Or, who knows, maybe you’ll prefer the booth’s cold, lean sound to the warm, lush sound of the better DACs on the other outputs.
While it’s a fast double precision 48bit fixed point mixer with additional bits of headroom over that for the channel effects sections and the mix bus they feed into, the mixer can otherwise be hard clipped at every input or output, so stay out of that top meter LED on all channels and master, and preferably, like all mixers, leave the second to top LED as your accidental safety at least. While the meters on it aren’t the last word of usefulness, they work well enough, and you should definitely not be running it with the peaks always at or below the 0dBVU nominal point. Run it reasonably hot, but don’t be stupid. The meters have some options, though not quite the number that the old Tascam X-9 had.
Speaking of the X-9, that DB4 booth out sounds kind of like that mixer, just not quite the same low-end drive.