I definitely think a ST-70 is the way to go, but I'm biased as I'm still using two of them. If you go that route, it's also a great introduction into the world of modification/DIY. If you find one for cheap with the original circuit, the bass response improves dramatically by simply adding capacitance (in the right spot). Good luck with the search.
Tube amp beginner
What is good tube amp for entry level?
around $500.
around $500.