Tube amp for Sourcepoint 8?

I wouldn't want a 50+ year old amp to be my main rig

@mdemaio Why? As long as the power supply has been properly refurbished its a pretty competent amp and also reliable. Plus it can give a decent spanking to a fair amount of new amps.

BTW in the case of the ST70 the bias rectifier should also be replaced.

You can reduce distortion by installing an adapter to allow you to use a 6GH8 as a driver tube instead of the 7199 The 6U8 is the same as a 6GH8. No other modification required.

The weakness of that amp is the 5AR4 rectifier which can't really handle two pairs of EL34s at full power. But as long as you don't push the amp hard it holds up fine. 

Thanks Atmasphere. I've really only kept the ST70 for sentimental reasons (my dad built it when I was in utero). It sounds great, but runs hot, needs to be biased frequently, is cosmetically OK but not particularly beautiful, and most of all I don't have space for an amp and preamp. So it's fine for what it is, but it's not the long-term answer. 

It sounds great, but runs hot, needs to be biased frequently

@mdemaio If it needs frequent biasing there's something wrong with it. One of the things that can cause that is that bias rectifier I mentioned. The original is a selenium device which in short is terrible. It can be replaced with a UA4007 which is a 15 cent part.

If you are wanting an integrated tube amp this is what you're up against. The ST70 is a good minimum power for your speakers unless you are in a smaller room (which might be the case if space for the amp is that tight; if that's true skip the next part). The space needed to make that kind of power means that if the amp is integrated its going to take up some room (unless it has really cheap output transformers), more than an ST70.

Do you need a phono section? If no, you might be able to run everything through your DAC.

If you skipped the stuff above, a smaller amp will work if your room is smaller. You might be able to get by on only 15-20 Watts/channel. I mentioned the Dynaco SCA35 earlier; its compact and a nice sounding amp if properly sorted out (there may be new ones around too). You might also look out for a Sansui AU-111. Sansui made this amp in the 1960s but reproduced it in the 1990s due to popular demand. Very nice design and it makes 40 Watts/channel.