Pass Labs XA30.8 vs XA60.8 moon blocks

The Chapman T7s are 4 ohm speakers with 90dB sensitivity 

Moon blocks... Love those typos!

They should nickname the XA60.8 amps The Eclipse. Because they are Moon blocks.

I called Pass Labs with the same question. Recommendation for my speakers was X260.8. The XA60.8 will be an upgrade over XA30.8 not only because of higher power rating, which helps regardless, but also due to superior power supplies. Going from XA30.8 to X260.8 was a significant step up in my system. There’s lower noise floor, better detail and separation and bigger soundstage. Bass is on a totally different level.
The room is a touch warmer now as well but tolerable.
I would expect the same type of improvement going from XA30.8 to the XA60.8 monoblocks.

Call or email Pass Labs and get their thoughts on your upgrade path. Never hurts to hear it from them what to expect.

audphile1 has the right suggestion.  The people at Pass Labs are who you want to talk to.  They are very good about customer support, even if you didn't buy the amps new, and will give you the right advice.