Just to echo some of the other comments, here's my 2 cents. I think you'd be happy with either the Darlington or UP, I'd lean towards the UP for a couple of reasons. Cost, this is your first pre-amp and if you can save a couple of bucks to learn more about them and the sound your looking for why not. The MoFi pre-amps are theoretically designed for the MoFi decks, so you're definitely going to get a specific sound signature being generated, that said, I've had the StudioPhono and UltraDeck running a Grado Opus3 and they're a wonderful match..........plus your gaining a headphone amp on the UltraPhono.
My last bit of advice is this, while there are a ton of reviews, opinions, even from the fine folks here, including me, I'd always take it all in with a grain of salt. It's good to hear that a piece is solid and gets the nod from the majority of it's users, but the honest reality is that we all have our own ears, preferences and gear set ups. So while all the opinions are great to have and serve as a great guide, use it as a filter to get to something that appeals/interests you by comments and try it out. Which brings me full circle, if you're wanting to "try it out" go with the deal for now and figure out what you're looking for
You might be perfectly happy right out of the gate with either of these, you never know. But hanging around here, highly unlikely, lol. For the most part anyone who chimes in around here is speaking from long term experience with something and I'd give their thoughts a little more weight, but they're my people, and we've been on many interesting gear paths over the years.
Last note, you gotta try a Grado at least once. I still have my Opus3 and currently running a Sonata3, love them both.
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