Uwbadger...McIntosh and ARC are very different sounding tube gear. I think the only way to answer your question is to see if you can hear them for yourself (I know easier said than done). I have heard the C2300 and I went with the Ref 3 as I found it to be much more resolving, more 3 dimensional and presented tighter/quicker leading edges to transients and was punchier and more articulated in the bass frequencies. It's also more open and airier. But the McIntosh C2300 was a more forgiving sound. It had a warm coloration which it brought to the party. The ARC was more transparent for me and hence let more of the input signal pass through to the amps untouched vs. the C2300. I have not heard the new C2500 or the new Ref 5SE so I can't help you with these newer models but if they are cut from the same cloth as their predecessors, hopefully the above will give you, at least one person's opinion of what they heard when they auditioned both pieces of gear. If you can get both pieces into your house at the same time to audition that would be ideal. I can tell you that ARC and Vandy have always been good combos as have ARC and Ayre (Ayre and Vandies is also a very frequent coupling), so I don't think you can go wrong on that front.
On the issue of money, you will definitely be spending way more with the Ref 5SE as that is already double the C2500 I believe and has no on-board phono stage, so you are talking a big step up in expense, so that is another major consideration. You mention you want non-fatiguing sound (we all do for sure) and a preamp that will be kind to crappy digital and the McIntosh may fit that bill for sure but that may come at the cost of dulling the resolution a bit, of darkening the overall tonal balance, and maybe less extension and articulation at the frequency extremes.
Once again, my reco would be to audition both and see which one is your cup of tea. Hope this helps.
