If you are that serious about sound quality, then in my opinion you should first pony up some serious money for high performance amplification, loudspeakers, and an acoustically treated listening environment to reliably hear differences. Loudspeakers are pretty much the highest source of distortion in the audio chain, so I reckon that this is where money should be spent for real audible improvements.
To build good gear does cost, but (I strongly suspect) not as much as the "top shelf" might suggest. Most convertors use one of a handful of AD chips which cost maybe $10 or less each in bulk buys. Price can reflect the robustness and durability of equipment - heavier duty casing and fastenings for example - which may be a wiser investment for equipment going on the road.
Current generation oversampling AD chips all perform very well. Audible differences in converter hardware may come down to:
The analog conditioning circuit prior to conversion.
PCB layout.
Quiet power supply with appropriate de-coupling for individual ICs.
Good clocking (probably less of an issue today). Good quality connectors. Shielding.
I believe that the engineering design principles are pretty well defined these days, and the audible differences between competently designed pieces of hardware will be fairly subtle - although plenty of punters will stridently disagree.
I therefore think there are other areas to explore before fussing too much about converters.
Maybe you have some anxiety about not having the "best"? How about going out and auditioning equipment to put your mind at ease? If, under controlled listening conditions, you can repeatedly and reliably hear a clear difference in gear, then go for it. Remember, "pro" audio is not in any way free from hype and marketing.
You might find Ethan Winer's Audio Myths workshop interesting.
Audio Myths Workshop - YouTube
Good luck!
Paul