if i buy a small tube amp like a little giant by blackheart and throw on a rp-250 or my ds-1 will it sound good at low amp volumes or do i need to crank it?
It would sound a lot better when cranked, but it will be alright if you get the blackheart little giant because you can turn it to 3 watts if it's too loud. I'm not a fan of digitech or Boss pedals so I wouldn't know how they would sound.
Eh, putting a DS-1 in front of it won't sound great. I know from personal experience, a DS-1 in front of anything doesn't sound great. Why don't you buy a small tube amp and a good overdrive pedal.
it'll sound alright, but yea, the nicer the OD pedal, the nicer the sound will be at lower volumes.

get an OCD or Fulldrive OD and it'll sound great.

but if you're rarely gonna be able to crank it, get a Vox AD30VT or something similar.
My MAIN Gear
"They call him the 'Sand Spider.' -Why? -Probably because it sounds scary"
*Agile AL3000 Les Paul w/ Alnico IIs
*Randall RM50
*Dunlop CFH
*fellow LEO feel free to give a shout out