Now this is just my tastes and this is on sound quality alone with the NX-Oticas specifically and excluding things like diy vs production vs reliability. Adding a couple preamp/amp combos as I feel the combo has some special synergy that sets them apart from the rest. A few are tied and some of these in the middle and back tend to switch around depending on music type so this is in general as best I can. I'm not including amps I feel are not worth it at all.
PSAudio BHKPre/300monos, Hypex preamp/Nilai500, Folsom7293/GR Research GK10, VTV Purifi Eval1/VTV Purifi Monos w/Neurochrome buffer, Elekit TU8600s, Neurochrome Mod86/286/686, Akitika GT104, First Watt AlephJ, Benchmark AHB2, Akitika GT102/AiyimaA08Pro, Emotiva XPA2 gen2.