I have no experience with this but am contemplating pre-amps for the UR44 cause of low input gain.
However I’m thinking a Triton FetHead http://tritonaudio.com/fethead.html.
Is your priority quality or gain? The pre-amps in the UR series are praised alot so I suppose this justifies the price-range of your two options but still… they’re more expensive than your AI.
Also, I’ve been having this weird discussion with Steinberg support asking about pre-amps. First of all, they won’t/can’t give advice about other products but secondly (and this is the weird part) they say you can’t bypass the internal pre-amps but this seems odd to me. Yet, it’s their official response so something to consider…