So will the fosi Audio V3 not work particularly well with just a phono output from a phone ?
No it's not, why would you say thatNot sure if you realise but they're "mono" amplifiers so you need a pair of them and an appropriate in which case they'd work well .... if you only want a single amp their ZA3 may be a better choice.
I'm guessing you already have speakers or will you be looking for those as well?

No it's not, why would you say that
