nad m25 no thx logo on front

My m25 does not have a thx ultrs2 logo on the front right corner all the other models have one NAD said that newer production models did not come with one but it does have thxultra2 info on the back panel also what would be the biggest mains/center/rear speakers this thing could drive currently running b&w804n htm2 center klispch rears.
The M25 is a pretty potent multichannel amplifier.

Are you considering a full setup of B&W, Klipsch, or some other brand?

If Klipsch, your NAD would have no problem driving a full RF-7II(RF-7II's, RC-64II, RS-62II's) setup. Can't say about B&W.