I've never heard either the Sophia or the Anthem amps, sorry.
If you're looking in the $500-600 range I'd recommend a Quicksilver GLA or a Rogue Stereo ? (I think it's Stereo 70 or 80, not sure). You could get either in your pricerange used and both are excellent amps. Neither are currently available on agon but worth the wait. If you can spend a little more there's a Music Reference RM-10 on Agon with extra tubes for 1,075. That's a fantastic amp!
Welcome to tubes!