Nothing wrong with the highs in the XP-20 - a little more emphasis on leading edge than the ARC. I don't mean to suggest the pre-amp is bright or siblant. You already know it isn't if you own it. As typical with tubes, ARC highs have a little more airiness, and sweetness. This may be great for female vocals, less so for hard rock guitar solos. It would be best if you could listen yourself and compare.
If you are into vinyl, I would tend to use electronics that you find to be the most neutral, transparent and resolving and then tailor the sound slightly with your choice in cartridges.
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