The data delivered to Bartok from your Synology NAS or from another type of NAS such as Melco will be the same. So from that viewpoint you will gain no advantage. However others here have moved from an IT type NAS to an audio orientated one with reported subjective gains to SQ.
I use a Melco as NAS and it sounds superb. However my original choice of it was not based upon any potential gain in SQ but rather that because of my home layout it is not easy to situate a server in another room. So the NAS server needs to be in my listening room and a silent device ( no sound of spinning drives) was preferred. The Melco ( and my one uses HDDs) is completely mechanically inaudible except via a stethoscope or with ear pressed against the case.
Bartok , as with all dCS network products, has a network input . As your objective is best sound then this is the input that you need to use. Some of the devices you mention do not feature this interface and you would need to use USB which is inferior.
The Bartok streamer is of much higher quality than that provided by some of those alternatives not least because you have to use USB with them . Melco does offer a network connection and which they term as direct. If nothing else it makes the physical connection of NAS to dCS simple.
I can only suggest that as you already have a functioning system for playing local files you arrange for a demonstration of any alternative to find out if it really offers any advantage to you before committing money.