@smodtactical That is the opposite issue I am having. I am thinking I want a bit less warmth than the CODA #16 with the NS5000. I love the #16 and the full range sound with the NS5000 is excellent. My issue is that I use the top end of the Benchmark AHB2 as my reference. Though, I do not think even mono AHB2 will sound as good overall as the #16. I may get a pair of AHB2’s for a home trial. Another amp is SimAudio that should work but at a higher cost.
I moved the #16 to my office today with the Magenpan LRS+ and that is a great combo. I think the LRS+ is a bit brighter than the NS5000 so it seems to be a perfect fit with the Class A #16. I think I will be using the LRS+ and #16 together going forward.
Your comments about fatigue with the PASS makes me wonder if your issue is a room acoustics problem. Why not measure your room acoustics and see if that is the cause of your fatigue.
Mitch Barnett from Digital Room Correction (DRC) Calibration - Accurate Sound can help you with your room acoustics. You do not have to use his software-based solution, you could choose physical room panels instead. However, getting a professional to help you sort the room out was the best move I made in my small office. He charges $700 for the measurements and the resulting convolution filters made for your speakers and room.
If you try this out for a month or so you can see if you still get the fatigue. If not, then it is not the gear. You can save a lot of money by fixing the room and not chasing gear. You can then fix the room with panels or Mitch’s filter or a combo of both. I use panels only in my office.