Hello Groundhog,
If using more than one source, like you with the CD, Tuner, and reel to reel, it is best to use an active preamp or you will need to really do a balancing act to have separate gain from each source and diferent impedance each also. I am sure your ST-70 has enough gain, but impedance matching all the sources is a problem.
Its not impossible, but complicated.
You can also get a good active preamp, vintage amps (I have several) like newer preamps IMHO.
If you decide to go with one source only, the passive will work just fine.
All the Best
PS: Placette Audio has a passive preamp designed for various sources, you can check them out.