Pass xa600.5, Marantz 9S2 or Mcintosh MC501/MC601?

I have not heard the Tylers, but I did compare the 501s with the Marantz MA9S with Thiel 3.7s and ended up choosing the Marantz amps. The 501s were very nice but seemed to not be as extended in the high frequencies as the Marantz. The 501s sounded more tube like, as least in comparison to the Marantz. The Marantz do not exhibit any of the typical warm house sound (OK maybe just a hint of it)of that brand, but instead have a clarity and lack of coloration I really like. They also seem to have unlimited power and nice dynamics. Hope this helps.

Pass Labs. A very transparent amp.

I've compared an XA-30.5 to a McIntosh MC402 on Thiel 2.4s and the Pass beat it in every category, except bass control. I didn't get a chance to do a head to head, but I've also tried out an X250.5 and it was close enough to the XA-30.5 that I'm sure it would also handily best the McIntosh (while also addressing the bass issue). To be honest, I was shocked at the extent to which Pass beat the McIntosh.

Another vote for he Pass Labs.

I have Tyler Acoustics Linbrook Signature system speakers with a Pass XA30.5. They are definitely a synergistic match for each other. At higher volumes (90db) the needle moves past noon, so at some point I'd like to move up the line and get a more powerful Pass amp.

I can't comment on the other amps because I've never heard them.

I owned the Marantz and found it to be too polite. I own Pass now and have no desire to upgrade my amp anymore, having been through 5 amps, some a lot more expensive than the Pass. One was a McIntosh, which has a warm mid-range but somewhat flabby bass.