suggestions? Coda CSIB or Musical Fidelity M8xi?

Those are both great And Rotel Michi X5 might be a good addition to that list. Great amp. I own it and have been pleased.

I owned the almost latest CODA CSiB, #8, and now #16. I also own a Sanders Magtech that I bought used from Sanders for $4k. My understanding is that CODA built the Magtech for Sanders based on his design. I like the Magtech more than the CSiB and the #8. I like the #16 the best. I only have the Magtech and #16 today.

I am biased towards the Coda as I have a #8, and it is fantastic. I had a MF M3si for a short period years ago, and I really liked the sound. Sweet like the Coda. It was underpowered for what I needed at the time and I did not have the money to go up the MF chain, but I think I would have been happy with their sound. Personally I would not want the integrated DAC on the MF as it is unlikely it would offer the sound I want. Downside of the Coda is the button volume controls and clunky remote, but I would still vote for the Coda Option #1 with the most Class A watts. 

volume and clunky remote is my Rega, lol

that's been a known issue with these units unit though and sucks but not a deal breaker

I also have my eye on some contour 60i's which I'm not sure the rega can drive (higher sensitivity than my 40's but 4ohm vs the 6ohm rating on the 40's

and Rega does not publish any 4 ohm specs

quick update

went with a Hegel 390 and the bass control is exactly what I was seeking, the bass from these Dyns using a high power amp is exceptional

however

the Rega just crushes it in terms of musicality in my setup

I was oping for a 5k-ish solution and now suspect I may need to get closer to 10k for high power and musicality