Not sure about the Dayton. If it's like a Fiio E9 then it might not be low-z enough given your requirements. Also, based on your requirements, I would avoid any current mode type amplifier given you require low-z. Since your headphones are 25 ohms and 1W max I would proly consider a Schiit Magni. It is less than 0.1 ohms and delivers 1.2W into 32 ohms, so relative to your headphone needs, it is a high current amp. It is also $99 brand new and does not look like a POS.If you add a class-A operation requirement then go for the Asgard which can do 1W into 32 ohm.
You could probably also look into buying used Burson Soloist (Soloist SL) amps? I think the non-SL is like 4W @ 16Ohm or something like that?
Emotiva a-100? But then you'd need a adapter. I haven't tried it myself with my headphones though.
Oh, let's not forget about the Lake People/Violectric ones as well... I believe they pushed good power as well???
MalVeauX's guide on head-fi is pretty good and you can get a very cheap adapter made from one of the links provided on the OP. It's safe as long as you don't max out the volume. I can't speak for the amount of hiss/noise you'd get from a speaker amp though. Even with my virtue one.3's 55w into 4ohms, there is a very slight hiss when the room is silent and no music is playing.
