@kjl1065, personally I think only you can decide if something is a 'substantial upgrade' based on your room, system components, ears, preferences, etc...
Try to buy used at a decent price (allowing easy flip) or new with a return window. In my experience I've found spending substantially more on a DAC doesn't always translate to a 'substantial upgrade', but then sometimes it has been well worth it for me.
I recently sold my Meitner MA3 for a Weiss 205+LPS and the sonic trade-offs vs $ was well worth it for me. On the other hand I purchased a Yggy LIM while I owned the MA3, and as much as I liked it (for the $) couldn't live with the deltas and kept the more expensive Meitner.
To my ears the 204/205 is super clean, open, detailed, and fun. I thought it was a little lean and lacking in dynamics but the LPS helped with both of those. I wouldn't worry about the two box solution as both the DAC and LPS (e.g. Weiss, Modwright) are small, and even with my dual output Keces LPS the two combined take up less space than my Meitner did on my rack.
If you don't need USB try a used 205 (one for sale now at only $1600) with a $400ish LPS and see if you like the Weiss sound signature.
Cheers