Recommendation for Improvement over McCormack DNA-225

There is a Coda CSX listed on US Audio Mart for $2600.  

Went back and looked at the posting that I mentioned. It was posted by Coda,

@timlub , actually that one for $2600 was NOT posted by CODA.
CODA has two ads on US Audiomart. One for a 07X preamplifier for $3600 and one for a TSX amp for $5200.

I did see that ad for the CSX on US Audiomart, and contacted Doug Dale to verify the age/condition. He actually had a newer, refurbished CSX that he sold me for only a couple hundred more, with a two year warranty.
I'm still waiting on delivery, but having owned a Model 10, 20, and 11 amps, and the FET01 and 02b preamps previously, I am very familiar with the CODA brand. One of the reasons I tend to gravitate back towards them. Great sound for a good price.

For the OP, Yes, resale can be difficult, because CODA does not market themselves well. People love to throw money at names like Krell, Levinson, Rowland, companies that throw big money at glossy rags.
This does make for easier resale, but realize that those advertising/marketing fees are passed along to the customer.
In other words, in my opinion, a $5K list price CODA competes very well with $8-$10K brand that pays  top dollar for the marketing/glossy rag coverage. 

Only you can decide if you want to pay the extra money needed to buy a piece of gear that is well marketed, so that resale is easier.

CODA and Pass Labs are very good SS amps.
Clayton Audio also makes very good, smooth SS amps. Hard to find on the used market. You may be able to find a pair of M-100's monoblocks in your price range.