Will an Amp change improve my system ?

I have owned the following:

• CODA #8 (own CODA #16 now)
• Schitt Freya+
• Schitt Yggi+ OG and Yggi+ LIM (own these 2 now)
• Benchmark AHB2
• Schitt Mjolnir v3

I tried the Freya+ with the CODA #8 and did not like the amount of warmth I had. I liked the AHB2 and Freya+ the best with all the amps I used with the Freya+. I was not a big fan of the Freya+ and find that the Claas A Schitt Mjolnir v3 is better than the Freya+. Though it does not have a remote.

You have a lot of warm gear piling on top of each other. I know people like that type of setup, but I find a nudge towards neutrality when having a lot of warm gear really works for me. That is why the Benchmark AHB2 is what I would use if you keep the Freya+.

The Yggi+ LIM is my warm DAC. I need it for my bright headphones, where the Yggi+ OG is too revealing.

The AHB2 can be obtained from Benchmark for a 30-day home trial. If you want to spend a lot more the SimAudio 761 amp is what I consider the next version of the AHB2.

Another option is keeping all of the existing gear and try the Benchmark LA4 replacing the Freya+. It will be a totally different sound. A home demo is another option for the LA4.

BTW - I am trying to sell my Sanders Magtech (500 | 900 @ 8 | 4) that I use with Magnepan Minis because I need a different standby setup than the Sanders uses (it is automatic). It is an excellent amp. I am thinking of the new Schitt Wutan which can be put to standby manually. The Sanders would work nicely like the AHB2 to balance out a warm setup. It is warmer than the AHB2,

@OP GHD Prentice's post sums up the amplifiers very well. I would also add that if you like your Harbeths, then you will like the Pass. However, if you predominantly listen to rock music or large scale classical, and depending on your room size and seating position, you might want something with a bit more power - but that needs to be real power and not just watts on paper.

My opinion: run away from benchmark unless you like highly detailed sound! Check out the newer PS Audio amps/integrated amps, much better sounding than their older stuff. In the past, I purchased the top of the line Hegel integrated amps over the pass integrated, the Hegel sounded more natural and had a lot more power. Then when I got bigger speakers I went with the newer BHK PS Audio separate amp. Even the new class D ps audio amps sound very good.
Another opinion since your all digital like I am, I go straight from my dac to my amp, no need for a preamp as long as your dac has very good volume control. When I sold off all my analog stuff many years ago, I had a $5000 preamp and when I bypassed the preamp and went straight from the dac to the amp, sq improved, so I sold the preamp with the extra set of cables. 
 

@yyzsantabarbara If you are from Santa Barbara you might know or heard of my brother-in-law Judge Joe Lodge who passed recently after being the longest serving judge in California history.

Of the amps you have listed I can vouch for the Coda s5.5  It has 100 amps of high current and should drive the 6 ohm Harbeth easily. It is a very good amp, I love mine. My system is in my user page. What I love about my Coda is it tells you everything that's going on, yet is so sweet and delicate with a midrange tonality I have yet to hear better. (Better than my old VAC amp) I have never heard Harbeth speakers before but I have read that their known for their fantastic midrange. The Coda may work well to bring that out of them for you. Good luck with your search. Reach out to @vinylvalet for info on the Coda if interested, he is a great guy to deal with.