How big of a difference do amps make?

Contrary to Schubert, I drive my Aerial 10T with Sunfire SRA(bought NOS $450). Feels like I need a-bit more power of let's say Sunfire 300(used $700) and I'm sure that it will sound waywayway better than $200Kef with Halcro or Mark Levinson monos. At the same time I don't think that mine do well with 30wpc OTL tube amps or vintage Fisher receiver due to lack of power.

Without sufficient power to the specified load of the speaker neither price or sonic performance copmarison relevant.

Depends on the speakers. Some just can't make use of extra power. Matching amps to speakers is more important.

Cue Ralph's link to the "power paradigm"...

I had to look up the HK Citation 16--apparently it's still a fairly well respected amp (?).

Also your question is very theoretical--you'd do better asking "what amp is best for Merlin TSM's"--& there are tons of threads already on that. But yes, most people use tubes with Merlin's.

But with a "cheap cdp", your system will only sound as good as the "cheap cdp".....with expensive speakers like Merlins, it's like putting Pep Boys tires on a new BMW......

Steveaudio hits the nail on the head. What are you doing with a 'cheap' cdp and thinking about a better (or different) amp. I have little doubt that the Thor will sound better, but why bother if you really can make a much bigger change with a new CDP.

But that said, if getting the Thor (or any other amp which you feel is better for your Merlins) is just your first step in getting ready to seriously explore quality (not necessarily expensive though) CDP's have at it.

I can't recall how often I've said this. Once you get used to the attributes of all your other gear, guess what you then start listening to, again? Your amp. Which will always be the most identifiable piece of gear in your system. You will hear through every other piece very quickly.