Integrated to drive PSB Imagine T's in large room

I have a SimAudio i-1 (50wpc) integrated and it's plenty loud in my room (24 x 13 x 8). Keep in mind, the Imagines are 4 ohms, so essentially you're amp will be putting out 100w. Just make sure the Naim can handle a 4 ohm load. My Sim and the PSB's sing!

You clearly seem to have a preference for a warmer amp. I would think you might want to stick with the English sound. Thus the Creek and the Naim although the Plinius sounded awfully good to my ears as well. I agree that Naim tends to under rate their power. Remember it is peak music power before the onset of clipping that you need. Several higher end companies tend to underate power for reasons that elude me. For instance I own a Jadis Da 60 with 8 KT 88 power tubes and it sure doesn't sound like a mere 60 watt amp. Most amps with that many output tubes especially the KT 88 will rate their amps at 80 to 100 watts. In addition the power and output trannies are massive and this 60 watt amp weighs about 80lbs.
In your case I would think the Bel Canto while garnering superb reviews has a house sound that is quite crystaline and may not be your cup of tea.

@Jaybo - Denon DRA 635R, which is now powering my kitchen/porch speakers.

what denon gear? it maybe good stuff.

I have a Naim 140 amp and it works well with my psb gold stratus is. Naim is conservatively rated. Also have heard Sim Audio and also excellent. PSB are fairly sensitive.