The Best Preamp is no Preamp?

Absent an (active) preamp one is effectively listening to the source device's output stage, which is most cases has been designed to drive a preamp and not a power amp. In addition, many digital volume controls lose resolution at lower signal levels. In your specific case, it's relevant that the Chord equipment has both a very well designed output stage and a very high quality digital volume control implementation. I'm not surprised that the setup sounds better than with the Marantz in circuit. Not only are you eliminating the electronics, but a set of interconnects. To echo previous posts, given well designed source electronics, no preamp will most likely be better than a poor one. Lastly, preamps  generaly do, of course, provide source switching which many people need - statement of the obvious perhaps, but relevant nonetheless.

Over the many decades I have owned various passive pres, autoformers, stepped attenuaters, dedicated preamps/dacs (tube/ss), and for a couple years now, what I think is the best opf them all: Audio Alchemy DDP-1 + PS 5 (PS -5 being essential to optimize the DDP-1). I am surprised dac/pres aren't more popular. Mine saves shelf space, PLUS an extra; digital cable, power cord and isolation devices

Brandonhifi the Qutest is not designed to drive an amp directly. There if this is your intent  I would look at the Hugo2 at a minimum as it has some form of volume control. The TT2 and Dave a designed with this use in mind. For my money the best implementation of a dac as a preamp is by MSB but you are talking about a lot more money to get into one of their dacs. 

The best preamp is no preamp only until you hear high quality active preamp. The added resolution, transparency one may hear sans pre vs lower quality pre is generally initial novelty Many will discern analytical flavor over longer term, seek out pre to add, others may assume this as good as it gets, until they hear the magic that great active pre can bring to the table. I can easily convince myself my active pre is most important component in my system, it was game changer for me.

Streaming directly to my power amp on my second system for years. In my First Second System, I had an amplifier with gain controls and a Denon CD player that also provided some limited volume control. Plugged the CD player in direct to the power amp. Great sonic result and it’s simpler to manage. Even simpler now with streaming. 
 

Since the OP mentioned a Marantz preamp, will also say that I’m very happy with the sound of my main rig setting my AV7001 in PureDirect mode. I need a preamp on my main rig because of all the input devices to control.  But it just seems to make sense that if I can cut out a layer of electronics, I’ll get closer to the actual source signal. This seems analogous to hearing a Direct-To-Disk vinyl record vs ones that were made mixed and mastered the usual way.